1. Pythagoras theorem statement

2. 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) = =
AC2 = 900
Ans: The length of AC is 30

3. 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 = =
BC2 = 144
Ans: The length of BC is 12

4. 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 = =
AB2 = 64
Ans: The length of AB is 8

5. 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.