Q.

In the given figure, tangents PA and PB to the circle centred at O, from point P are perpendicular to each other. If PA = 5 cm, then length of AB is equal to

1 5 cm  
2 52 cm  
3 25 cm  
4 10 cm  

Ans.

(2)

PA = PB (Tangents from an external point P)

APB is a Right angle Triangle

AB2=AP2+PB2  [AP = PB]

AB2=2AP2

AB2=2×52

AB=52 cm