Pythagoras theorem statement
Example 1 : In ∆ABC, ∠B = 90o , AB = 18cm and BC = 24cm. Calculate the length of AC. Solution: Since ∆ABC is a right angled triangle AC2 = AB2 + BC2 (Pythagorus Theorem) = 182 + 242 = 324 + 576 AC2 = 900 Ans: The length of AC is 30
Example 2 : In ∆ABC, ∠B = 90o , AB = 5cm and AC = 13cm. Calculate the length of BC. Solution: Since ∆ABC is a right angled triangle ∴ AC2 = AB2 + BC2 (Pythagorus Theorem) BC2 = AC2 - AB2 = 132 - 52 = 169 - 25 BC2 = 144 Ans: The length of BC is 12
Example 3 : In ∆ABC, ∠B = 90o , AC = 17cm and BC = 15cm. Calculate the length of AB. Solution: Since ∆ABC is a right angled triangle ∴ AC2 = AB2 + BC2 (Pythagorus Theorem) AB2 = AC2 - BC2 = 172 - 152 = 289 + 225 AB2 = 64 Ans: The length of AB is 8
Try these In ∆ABC, ∠B = 90o , AB = 3cm and BC = 4cm. Calculate the length of AC. In ∆ABC, ∠B = 90o , AB = 24cm and AC = 25cm. Calculate the length of BC.