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 $$ = \frac{{10\sqrt 3 }}{2} = 5\sqrt 3 $$
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