Sir how i solve this question of class 10th of exercise 10.2 of ncert math of question no.6, give me the best and simple way to solve this question The length of a tangent from a point A at distance 5 cm from the centre of the circle is 4 cm. Find the radius of the circle.

AnilSinghBoraGuru

# The length of a tangent from a point A at distance 5 cm from the centre of the circle is 4 cm. Find the radius of the circle. Q.6

Share

Draw the diagram as shown below.

Here, AB is the tangent that is drawn on the circle from a point A.

So, the radius OB will be perpendicular to AB i.e. OB âŠ¥ AB

We know, OA = 5cm and AB = 4 cm

Now, In â–³ABO,

OA

^{2}=AB^{2}+BO^{2 }(Using Pythagoras theorem)5

^{2 }= 4^{2}+BO^{2}BO

^{2}= 25-16BO

^{2}= 9BO = 3

So, the radius of the given circle i.e. BO is 3 cm.