The length of a tangent from a point A at a distance 5 cm from the centre of the circle is 4 cms. Radius of the circle is
Solution
Here, AB is tangent of the circle with centre O. OA is the distance of A from centre O. $$\triangle$$ OAB is a right angled triangle right angled at B. $$OA^2 = AB^2 + OB^2$$ => $$5^2 = 4^2+OB^2$$ => $$25 = 16+OB^2$$ => $$OB^2 = 9 => OB = 3$$ Therefore, Radius of the circle = 3 cm.