Pythagoras and trigonometry
Lesson 4 of 14
Introduction
Pythagoras' theorem
Objective. Find a missing side in a right-angled triangle.
- 1. Learn
- 2. Worked example
- 3. Practice
- 4. Feedback
- 5. Continue
Learn: the key idea
a² + b² = c², where c is always the hypotenuse — the side opposite the right angle.
Worked example
A right triangle has legs 5 cm and 12 cm. Find the hypotenuse.
- 15² + 12² = 25 + 144 = 169.
- 2√169 = 13.
Answer: 13 cm
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