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Question
From a point P, the length of the tangent to a circle is 24 cm and the distance of P from the centre of the circle is 25 cm. Find the radius of the circle.
Solution
Let the radius of circle be r cm
ΔOPQ, ∠Q = 90°
∴ OP2 = OQ2 + PQ2
(25)2 = r2 + (24)2
625 – 576 = r2
49 = r2
r = ± 7
∴ Radius of circle = 7 cm
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