Question

$△$ABC is right angled at A. If BC = 60 cm and AC = 61 cm, then AB = ____________ cm.

• A. 11
• B. 12
• C. 21
• D. 51

Answer 1

The correct option is A

11

In a right angle triangle, Pythagoras Theorem states that the sum of the squares of the sides containing the right angle is equal to the square of the hypotenuse.

Therefore,$A{B}^2+A{C}^2=B{C}^2$

Thus, $A{B}^2=B{C}^2-A{C}^2$

$A{B}^2={61}^2-{60}^2$

$A{B}^2=3721-3600$

$A{B}^2=121$

$A{B}^2={11}^2$

AB = 11 cm