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Question

In the figure P is a point which is 12 cm away from the centre of the circle O. A line drawn from P point cuts circle at point A and B respectively. If PB = 9 cm, AB = 2 cm Then find out the radius of the circle?

A 6 cm Correct Answer Incorrect Answer
B 3 cm Correct Answer Incorrect Answer
C 9 cm Correct Answer Incorrect Answer
D 5 cm Correct Answer Incorrect Answer

Solution

Let the radius of a circle = r cm. PO = 12 cm then, PC = 12 cm - r PC = 12 - r PD = 12 + r ∵ PB = 9 cm AB = 2 cm ∴ then PA = 9 - 2 = 7 cm PA × PB = PC × PD 7 × 9 = (12-r) (12+r) 63 = 144 - r² r² = 144 - 63 = 81 r = √81  r = 9 cm

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