What is the formula for the circumference of a circle in Cambridge IGCSE Mathematics?

In Cambridge IGCSE Mathematics, the circumference of a circle is calculated using the formula C = 2πr, where 'C' represents the circumference and 'r' is the radius of the circle. Alternatively, if the diameter 'd' is known, the formula can be expressed as C = πd.

How do you calculate the area of a circle in Mensuration?

To calculate the area of a circle in Mensuration, use the formula A = πr², where 'A' is the area and 'r' is the radius of the circle. This formula is essential for solving problems related to circles in the Cambridge IGCSE Mathematics curriculum.

What is the difference between the radius and diameter of a circle?

The radius of a circle is the distance from the center of the circle to any point on its circumference, while the diameter is the distance across the circle, passing through the center. The diameter is twice the length of the radius, expressed as d = 2r.

How can you find the length of an arc in a circle?

The length of an arc in a circle can be found using the formula L = θ/360° × 2πr, where 'L' is the arc length, 'θ' is the central angle in degrees, and 'r' is the radius of the circle. This concept is part of the Mensuration topic in Cambridge IGCSE Mathematics.

What is the significance of π (pi) in circle calculations?

In circle calculations, π (pi) is a mathematical constant approximately equal to 3.14159. It represents the ratio of the circumference of any circle to its diameter and is crucial in formulas for calculating the circumference and area of circles in Cambridge IGCSE Mathematics.

Why is "Using diameter instead of radius (or vice versa)" a common mistake in Circles?

Why it happens: Reading the question too quickly. How to avoid it: Note: C = d = 2 r. If the diagram gives diameter, halve it before using A = r^2.

Why is "Using radians in the $\theta/360$ formula" a common mistake in Circles?

Why it happens: Calculator left in radian mode. How to avoid it: 0580 always uses degrees. Set the calculator to DEG mode at the start of the paper. Source: 0580/42 — recurring

Why is "Calling a sector a segment" a common mistake in Circles?

Why it happens: Mixing up the two regions. How to avoid it: Sector = two RADII + arc. Segment = one CHORD + arc.

Why is "Using $\pi r^{2}$ for arc length" a common mistake in Circles?

Why it happens: Mixing up area and length formulae. How to avoid it: Length comes from circumference 2 r. Area comes from r^2.

MensurationCambridge IGCSE Mathematics (0580)

Circles

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Circles, Arcs and Sectors — Cambridge IGCSE 0580 Maths Extended (2026)

Circumference, area, arc length, sector area and segment area. The fraction $\dfrac{\theta}{360}$ is the master tool — apply it to whichever full-circle quantity you want.

What you’ll learn

Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).

E6.3 — Calculate circumference and area of circles.
E6.4 — Calculate arc length and sector area.
E6.4 — Calculate area of a segment of a circle.

Circumference and area of a circle

$C = 2\pi r$ , $A = \pi r^{2}$ . Identify radius vs diameter first.

Formulae. $C = 2\pi r = \pi d, \qquad A = \pi r^{2}.$

The radius $r$ is half the diameter $d$ . Always check which the question gives you.

Worked. Circle radius $7\,\text{cm}$ . Find $C$ and $A$ to 3 s.f.

$C = 2\pi \times 7 = 14\pi \approx 44.0\,\text{cm}$ .
$A = \pi \times 7^{2} = 49\pi \approx 154\,\text{cm}^{2}$ .

Worked (diameter given). Diameter $20\,\text{cm}$ → radius $10\,\text{cm}$ .

$C = \pi \times 20 = 20\pi \approx 62.8\,\text{cm}$ .
$A = \pi \times 100 = 100\pi \approx 314\,\text{cm}^{2}$ .

Calculator $\pi$ button. Use the calculator's $\pi$ key — don't type $3.14$ unless the question says to.

$C = 2\pi r = \pi d$ .
$A = \pi r^{2}$ .
Radius $=$ diameter $\div 2$ .
Use exact $\pi$ , round at the end.

Arc length and sector area

Multiply the full-circle quantity by $\dfrac{\theta}{360}$ to scale to a sector of angle $\theta$ .

A sector is the pie-slice region of a circle bounded by two radii and an arc. The angle at the centre is $\theta$ (in degrees).

Arc length. $L = \dfrac{\theta}{360} \times 2\pi r.$

Sector area. $A_{\text{sector}} = \dfrac{\theta}{360} \times \pi r^{2}.$

The pattern: $\dfrac{\theta}{360}$ is the FRACTION of a full revolution, so it scales any full-circle quantity to its sector value.

Worked. Sector with radius $9\,\text{cm}$ and angle $80\degree$ .

Arc: $L = \dfrac{80}{360} \times 2\pi \times 9 = \dfrac{2}{9} \times 18\pi = 4\pi \approx 12.6\,\text{cm}$ .
Area: $A = \dfrac{80}{360} \times \pi \times 81 = \dfrac{2}{9} \times 81\pi = 18\pi \approx 56.5\,\text{cm}^{2}$ .

Perimeter of a sector. Two radii plus the arc: $P_{\text{sector}} = 2r + L.$

A common Cambridge trip-up: students forget the two radii.

Arc: $L = \dfrac{\theta}{360} \times 2\pi r$ .
Sector area: $\dfrac{\theta}{360} \times \pi r^{2}$ .
Sector perimeter: $2r + L$ (two radii + arc).

Segment of a circle

Segment area $=$ sector area $-$ triangle area. Use $\dfrac{1}{2}r^{2}\sin\theta$ for the triangle.

A segment is the region between a chord and the arc it cuts off — a sector with the central triangle sliced away.

Formula. $A_{\text{segment}} = A_{\text{sector}} - A_{\triangle} = \dfrac{\theta}{360}\pi r^{2} - \dfrac{1}{2}r^{2}\sin\theta.$

The triangle formed by the two radii and the chord has area $\dfrac{1}{2}r^{2}\sin\theta$ (see Trigonometry — area rule).

Worked. Segment in a circle radius $10\,\text{cm}$ , central angle $60\degree$ .

Sector area: $\dfrac{60}{360}\pi \times 100 = \dfrac{50\pi}{3} \approx 52.36\,\text{cm}^{2}$ .
Triangle area: $\dfrac{1}{2} \times 100 \times \sin 60\degree = 50 \times \dfrac{\sqrt{3}}{2} \approx 43.30\,\text{cm}^{2}$ .
Segment: $52.36 - 43.30 \approx 9.06\,\text{cm}^{2}$ .

Major vs minor segment. The chord splits the circle into a minor (small) and major (large) segment. The formula above gives the minor segment for $\theta < 180\degree$ .

Segment $=$ sector $-$ triangle.
Triangle area: $\dfrac{1}{2}r^{2}\sin\theta$ .
Minor segment: $\theta < 180\degree$ .

Units, rounding and exact answers

Keep $\pi$ exact through the calculation. Round only at the end (3 s.f. unless told otherwise).

Exact vs decimal answers.

"Give your answer in terms of $\pi$ " → leave $\pi$ in the answer (e.g. $4\pi\,\text{cm}^{2}$ ).
"Give your answer to 3 significant figures" → use the calculator's $\pi$ button, round only at the end.

Common error. Rounding $\pi$ to $3.14$ early in a multi-step calculation. This compounds errors and can lose marks.

Units.

Lengths and arc lengths: linear units ( $\text{cm}, \text{m}$ ).
Areas: squared units ( $\text{cm}^{2}, \text{m}^{2}$ ).
Always include the unit in the final answer.

Use the calculator $\pi$ key.
Round only at the end (3 s.f. typical).
Always include units.

How it’s examined

Circle, arc and sector questions appear every Paper 4 (3-6 marks each), often combined with composite-shape questions. Examiner reports flag forgetting the two radii in sector perimeter as a frequent error. Exact- $\pi$ answers are increasingly preferred — read the question.

Sources: Cambridge IGCSE Mathematics 0580 syllabus 2025-2027 (E6.3-6.4); 0580/42 Oct/Nov 2024 — Q11 (sector + segment); 0580 Examiner Reports 2022-2024. Last reviewed 2026-05-05.

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Circles, ready to print or save as PDF.

Step-by-step worked examples — Circles

Step-by-step solutions to past-paper-style questions on circles, written exactly the way a tutor would explain them at the board.

1Circumference and area of a circle
Core• circle
Question
Find the circumference and area of a circle of radius $5$ cm. Give answers to 1 d.p.
Step-by-step solution
1. Step 1
  $C = 2\pi r$ .
  $C = 2\pi(5) = 10\pi \approx 31.4\,\text{cm}$
2. Step 2
  $A = \pi r^{2}$ .
  $A = \pi(25) = 25\pi \approx 78.5\,\text{cm}^{2}$
Answer
$C \approx 31.4\,\text{cm},\ A \approx 78.5\,\text{cm}^{2}$
2Arc length
Extended• Adapted from 0580/42 May/Jun 2024 Q13• arc length
Question
Find the length of an arc of a circle, radius $9$ cm, that subtends an angle of $80\degree$ at the centre.
Step-by-step solution
1. Step 1
  Arc length $= \dfrac{\theta}{360} \times 2\pi r$ .
  $L = \dfrac{80}{360} \times 2\pi(9) = \dfrac{2}{9} \times 18\pi = 4\pi$
Answer
$4\pi\,\text{cm} \approx 12.6\,\text{cm}$
3Sector area
Extended• sector
Question
Find the area of a sector of a circle, radius $6$ cm, with sector angle $120\degree$ .
Step-by-step solution
1. Step 1
  Sector area $= \dfrac{\theta}{360} \times \pi r^{2}$ .
  $A = \dfrac{120}{360} \times \pi(36) = 12\pi$
Answer
$12\pi\,\text{cm}^{2} \approx 37.7\,\text{cm}^{2}$
4Area of a segment
Extended• segment
Question
A chord subtends an angle of $90\degree$ at the centre of a circle of radius $4$ cm. Find the area of the minor segment.
Step-by-step solution
1. Step 1
  Segment area = sector area − triangle area.
  $A = \dfrac{90}{360} \pi(16) - \dfrac{1}{2}(4)(4)\sin 90\degree$
2. Step 2
  Compute.
  $A = 4\pi - 8 \approx 4.57\,\text{cm}^{2}$
Answer
$4\pi - 8 \approx 4.57\,\text{cm}^{2}$

Key Formulae — Circles

The formulae you need to memorise for circles on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.

Circumference
$C = 2\pi r = \pi d$
$r$
radius
$d$
diameter $= 2r$
When to use
Distance around any circle.
Area of a circle
$A = \pi r^{2}$
$r$
radius
When to use
Area enclosed by any circle.
Arc length
$L = \dfrac{\theta}{360} \times 2\pi r$
$\theta$
sector angle in degrees
When to use
Length of a portion of the circumference.
Sector area
$A = \dfrac{\theta}{360} \times \pi r^{2}$
$\theta$
sector angle in degrees
When to use
Area of a 'pie-slice' of a circle.

Key Definitions and Keywords — Circles

Definitions to memorise and the exact keywords mark schemes credit for circles answers — sharpened from recent examiner reports for the 2026 0580 sitting.

Radius
Examiner keyword
Distance from the centre to the edge of the circle.
Diameter
Examiner keyword
Distance across a circle through its centre $= 2r$ .
Arc
Examiner keyword
A portion of the circumference. Minor arc = shorter; major arc = longer.
Sector
Examiner keyword
A 'pie slice' bounded by two radii and an arc.
Segment
Region bounded by a chord and an arc.

Common Mistakes and Misconceptions — Circles

The traps other students keep falling into on circles questions — taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes — and how to avoid them.

✕Using diameter instead of radius (or vice versa)
Why it happens
Reading the question too quickly.
How to avoid it
Note: $C = \pi d = 2\pi r$ . If the diagram gives diameter, halve it before using $A = \pi r^{2}$ .
✕Using radians in the $\theta/360$ formula
0580/42 — recurring
Why it happens
Calculator left in radian mode.
How to avoid it
0580 always uses degrees. Set the calculator to DEG mode at the start of the paper.
✕Calling a sector a segment
Why it happens
Mixing up the two regions.
How to avoid it
Sector = two RADII + arc. Segment = one CHORD + arc.
✕Using $\pi r^{2}$ for arc length
Why it happens
Mixing up area and length formulae.
How to avoid it
Length comes from circumference $2\pi r$ . Area comes from $\pi r^{2}$ .

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Circles — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

MensurationCambridge IGCSE Mathematics (0580)

Circles

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

Previous Next

Learn this Topic

Start with the slides for the quick version, then go deeper with the full study notes.

Short Study Notes in the form of Slides

Read the notes first. If the method in a worked example clicks, you're ready for the questions.

Page 1 / 0

Detailed Study Notes

Full prose, callouts and a recap — built for A* mastery, not just a quick scan.

Take these study notes with you

Download a branded PDF — full prose, callouts, recap and memorise list for Circles, ready to print or save offline.

Circles, Arcs and Sectors — Cambridge IGCSE 0580 Maths Extended (2026)

Circumference, area, arc length, sector area and segment area. The fraction $\dfrac{\theta}{360}$ is the master tool — apply it to whichever full-circle quantity you want.

What you’ll learn

Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).

E6.3 — Calculate circumference and area of circles.
E6.4 — Calculate arc length and sector area.
E6.4 — Calculate area of a segment of a circle.

Circumference and area of a circle

$C = 2\pi r$ , $A = \pi r^{2}$ . Identify radius vs diameter first.

Formulae. $C = 2\pi r = \pi d, \qquad A = \pi r^{2}.$

The radius $r$ is half the diameter $d$ . Always check which the question gives you.

Worked. Circle radius $7\,\text{cm}$ . Find $C$ and $A$ to 3 s.f.

$C = 2\pi \times 7 = 14\pi \approx 44.0\,\text{cm}$ .
$A = \pi \times 7^{2} = 49\pi \approx 154\,\text{cm}^{2}$ .

Worked (diameter given). Diameter $20\,\text{cm}$ → radius $10\,\text{cm}$ .

$C = \pi \times 20 = 20\pi \approx 62.8\,\text{cm}$ .
$A = \pi \times 100 = 100\pi \approx 314\,\text{cm}^{2}$ .

Calculator $\pi$ button. Use the calculator's $\pi$ key — don't type $3.14$ unless the question says to.

$C = 2\pi r = \pi d$ .
$A = \pi r^{2}$ .
Radius $=$ diameter $\div 2$ .
Use exact $\pi$ , round at the end.

Arc length and sector area

Multiply the full-circle quantity by $\dfrac{\theta}{360}$ to scale to a sector of angle $\theta$ .

A sector is the pie-slice region of a circle bounded by two radii and an arc. The angle at the centre is $\theta$ (in degrees).

Arc length. $L = \dfrac{\theta}{360} \times 2\pi r.$

Sector area. $A_{\text{sector}} = \dfrac{\theta}{360} \times \pi r^{2}.$

The pattern: $\dfrac{\theta}{360}$ is the FRACTION of a full revolution, so it scales any full-circle quantity to its sector value.

Worked. Sector with radius $9\,\text{cm}$ and angle $80\degree$ .

Arc: $L = \dfrac{80}{360} \times 2\pi \times 9 = \dfrac{2}{9} \times 18\pi = 4\pi \approx 12.6\,\text{cm}$ .
Area: $A = \dfrac{80}{360} \times \pi \times 81 = \dfrac{2}{9} \times 81\pi = 18\pi \approx 56.5\,\text{cm}^{2}$ .

Perimeter of a sector. Two radii plus the arc: $P_{\text{sector}} = 2r + L.$

A common Cambridge trip-up: students forget the two radii.

Arc: $L = \dfrac{\theta}{360} \times 2\pi r$ .
Sector area: $\dfrac{\theta}{360} \times \pi r^{2}$ .
Sector perimeter: $2r + L$ (two radii + arc).

Segment of a circle

Segment area $=$ sector area $-$ triangle area. Use $\dfrac{1}{2}r^{2}\sin\theta$ for the triangle.

A segment is the region between a chord and the arc it cuts off — a sector with the central triangle sliced away.

Formula. $A_{\text{segment}} = A_{\text{sector}} - A_{\triangle} = \dfrac{\theta}{360}\pi r^{2} - \dfrac{1}{2}r^{2}\sin\theta.$

The triangle formed by the two radii and the chord has area $\dfrac{1}{2}r^{2}\sin\theta$ (see Trigonometry — area rule).

Worked. Segment in a circle radius $10\,\text{cm}$ , central angle $60\degree$ .

Sector area: $\dfrac{60}{360}\pi \times 100 = \dfrac{50\pi}{3} \approx 52.36\,\text{cm}^{2}$ .
Triangle area: $\dfrac{1}{2} \times 100 \times \sin 60\degree = 50 \times \dfrac{\sqrt{3}}{2} \approx 43.30\,\text{cm}^{2}$ .
Segment: $52.36 - 43.30 \approx 9.06\,\text{cm}^{2}$ .

Major vs minor segment. The chord splits the circle into a minor (small) and major (large) segment. The formula above gives the minor segment for $\theta < 180\degree$ .

Segment $=$ sector $-$ triangle.
Triangle area: $\dfrac{1}{2}r^{2}\sin\theta$ .
Minor segment: $\theta < 180\degree$ .

Units, rounding and exact answers

Keep $\pi$ exact through the calculation. Round only at the end (3 s.f. unless told otherwise).

Exact vs decimal answers.

"Give your answer in terms of $\pi$ " → leave $\pi$ in the answer (e.g. $4\pi\,\text{cm}^{2}$ ).
"Give your answer to 3 significant figures" → use the calculator's $\pi$ button, round only at the end.

Common error. Rounding $\pi$ to $3.14$ early in a multi-step calculation. This compounds errors and can lose marks.

Units.

Lengths and arc lengths: linear units ( $\text{cm}, \text{m}$ ).
Areas: squared units ( $\text{cm}^{2}, \text{m}^{2}$ ).
Always include the unit in the final answer.

Use the calculator $\pi$ key.
Round only at the end (3 s.f. typical).
Always include units.

How it’s examined

Sources: Cambridge IGCSE Mathematics 0580 syllabus 2025-2027 (E6.3-6.4); 0580/42 Oct/Nov 2024 — Q11 (sector + segment); 0580 Examiner Reports 2022-2024. Last reviewed 2026-05-05.

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Circles, ready to print or save as PDF.

Step-by-step worked examples — Circles

Step-by-step solutions to past-paper-style questions on circles, written exactly the way a tutor would explain them at the board.

1Circumference and area of a circle
Core• circle
Question
Find the circumference and area of a circle of radius $5$ cm. Give answers to 1 d.p.
Step-by-step solution
1. Step 1
  $C = 2\pi r$ .
  $C = 2\pi(5) = 10\pi \approx 31.4\,\text{cm}$
2. Step 2
  $A = \pi r^{2}$ .
  $A = \pi(25) = 25\pi \approx 78.5\,\text{cm}^{2}$
Answer
$C \approx 31.4\,\text{cm},\ A \approx 78.5\,\text{cm}^{2}$
2Arc length
Extended• Adapted from 0580/42 May/Jun 2024 Q13• arc length
Question
Find the length of an arc of a circle, radius $9$ cm, that subtends an angle of $80\degree$ at the centre.
Step-by-step solution
1. Step 1
  Arc length $= \dfrac{\theta}{360} \times 2\pi r$ .
  $L = \dfrac{80}{360} \times 2\pi(9) = \dfrac{2}{9} \times 18\pi = 4\pi$
Answer
$4\pi\,\text{cm} \approx 12.6\,\text{cm}$
3Sector area
Extended• sector
Question
Find the area of a sector of a circle, radius $6$ cm, with sector angle $120\degree$ .
Step-by-step solution
1. Step 1
  Sector area $= \dfrac{\theta}{360} \times \pi r^{2}$ .
  $A = \dfrac{120}{360} \times \pi(36) = 12\pi$
Answer
$12\pi\,\text{cm}^{2} \approx 37.7\,\text{cm}^{2}$
4Area of a segment
Extended• segment
Question
A chord subtends an angle of $90\degree$ at the centre of a circle of radius $4$ cm. Find the area of the minor segment.
Step-by-step solution
1. Step 1
  Segment area = sector area − triangle area.
  $A = \dfrac{90}{360} \pi(16) - \dfrac{1}{2}(4)(4)\sin 90\degree$
2. Step 2
  Compute.
  $A = 4\pi - 8 \approx 4.57\,\text{cm}^{2}$
Answer
$4\pi - 8 \approx 4.57\,\text{cm}^{2}$

Key Formulae — Circles

The formulae you need to memorise for circles on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.

Circumference
$C = 2\pi r = \pi d$
$r$
radius
$d$
diameter $= 2r$
When to use
Distance around any circle.
Area of a circle
$A = \pi r^{2}$
$r$
radius
When to use
Area enclosed by any circle.
Arc length
$L = \dfrac{\theta}{360} \times 2\pi r$
$\theta$
sector angle in degrees
When to use
Length of a portion of the circumference.
Sector area
$A = \dfrac{\theta}{360} \times \pi r^{2}$
$\theta$
sector angle in degrees
When to use
Area of a 'pie-slice' of a circle.

Key Definitions and Keywords — Circles

Definitions to memorise and the exact keywords mark schemes credit for circles answers — sharpened from recent examiner reports for the 2026 0580 sitting.

Radius
Examiner keyword
Distance from the centre to the edge of the circle.
Diameter
Examiner keyword
Distance across a circle through its centre $= 2r$ .
Arc
Examiner keyword
A portion of the circumference. Minor arc = shorter; major arc = longer.
Sector
Examiner keyword
A 'pie slice' bounded by two radii and an arc.
Segment
Region bounded by a chord and an arc.

Common Mistakes and Misconceptions — Circles

The traps other students keep falling into on circles questions — taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes — and how to avoid them.

✕Using diameter instead of radius (or vice versa)
Why it happens
Reading the question too quickly.
How to avoid it
Note: $C = \pi d = 2\pi r$ . If the diagram gives diameter, halve it before using $A = \pi r^{2}$ .
✕Using radians in the $\theta/360$ formula
0580/42 — recurring
Why it happens
Calculator left in radian mode.
How to avoid it
0580 always uses degrees. Set the calculator to DEG mode at the start of the paper.
✕Calling a sector a segment
Why it happens
Mixing up the two regions.
How to avoid it
Sector = two RADII + arc. Segment = one CHORD + arc.
✕Using $\pi r^{2}$ for arc length
Why it happens
Mixing up area and length formulae.
How to avoid it
Length comes from circumference $2\pi r$ . Area comes from $\pi r^{2}$ .

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Circles — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Circles

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Circumference and area of a circle

2Arc length

3Sector area

4Area of a segment

Circumference

Area of a circle

Arc length

Sector area

Radius

Diameter

Arc

Sector

Segment

✕Using diameter instead of radius (or vice versa)

✕Using radians in the θ/360\theta/360θ/360 formula

✕Calling a sector a segment

✕Using πr2\pi r^{2}πr2 for arc length

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Circles — frequently asked questions

Circles

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Circumference and area of a circle

2Arc length

3Sector area

4Area of a segment

Circumference

Area of a circle

Arc length

Sector area

Radius

Diameter

Arc

Sector

Segment

✕Using diameter instead of radius (or vice versa)

✕Using radians in the θ/360\theta/360θ/360 formula

✕Calling a sector a segment

✕Using πr2\pi r^{2}πr2 for arc length

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Circles — frequently asked questions

✕Using radians in the $\theta/360$ formula

✕Using $\pi r^{2}$ for arc length

✕Using radians in the $\theta/360$ formula

✕Using $\pi r^{2}$ for arc length