Summary
Pythagoras' theorem is used to find unknown sides of a right-angled triangle by stating that the square of the hypotenuse is equal to the sum of the squares of the other two sides.
- Hypotenuse — the longest side of a right-angled triangle Example: In a triangle with sides 3 cm, 4 cm, and 5 cm, the hypotenuse is 5 cm.
- Opposite — the side opposite the angle of interest in a right-angled triangle Example: In a triangle with a 90° angle, if the angle of interest is 30°, the opposite side is the one directly across from this angle.
- Adjacent — the side next to the angle of interest in a right-angled triangle Example: In a triangle with a 90° angle, if the angle of interest is 30°, the adjacent side is the one next to this angle, excluding the hypotenuse.
Exam Tips
Key Definitions to Remember
- The hypotenuse is the longest side of a right-angled triangle.
- Pythagoras' theorem: , where is the hypotenuse.
Common Confusions
- Confusing the hypotenuse with the other sides.
- Forgetting to square the sides when using the theorem.
Typical Exam Questions
- What is the length of the hypotenuse if the other sides are 3 cm and 4 cm? Answer: 5 cm
- Find the missing side if one side is 8 cm and the hypotenuse is 10 cm. Answer: 6 cm
- Calculate the hypotenuse when the other two sides are 5 m and 12 m. Answer: 13 m
What Examiners Usually Test
- Ability to correctly apply Pythagoras' theorem to find unknown sides.
- Understanding of which side is the hypotenuse in a right-angled triangle.