Question: P is a point outside a circle and is 13 cm away from its centre. A secant drawn from the point P intersects the circle at points A and B in such a way that PA = 9 cm and AB = 7 cm. The radius of the circle is
Options:
A) 5.5 cm
B) 5 cm
C) 4 cm
D) 4.5 cm.
Show Answer
Answer:
Correct Answer: B
Solution:
- From figure,
$ PA\times PB=PQ\times PR $
$ \Rightarrow $ $ 9\times (9+7)=(13-r)(13+r) $
$ \Rightarrow $ $ 169-r^{2}=144 $
$ \Rightarrow $ $ r^{2}=25 $
$ \Rightarrow $ $ r=5,cm $