In the given figure, TB is a chord which passes through the centre of the circle. PT is a tangent to the circle at the point T on the circle. If PT = 10 cm, PA = 5 cm and AB = x cm, then the radius of the circle is:

A. 5√3 cm

B. 6√5 cm

C. 3√5 cm

D. 10√3 cm

Answer: Option A

Solution (By Examveda Team)

PA × PB = PT²
5(5 + x) = 100
x = 15
In right angle triangle PTB,
TB² = 20² - 10²
TB² = $$10\sqrt 3 $$
So, OT $$ = \frac{{10\sqrt 3 }}{2} = 5\sqrt 3 $$