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A tangent at point A of a circle of radius 5 cm meets a line through the centre at B such that AB = 12 cm. The length of OB is
A13 cm
B17 cm
C15 cm
D7 cm
Answer & Solution
Correct answer: A. 13 cm
1. Right triangle OAB right-angled at A.
2. OB squared = OA squared + AB squared = 25 + 144 = 169.
3. OB = 13 cm.
_Source: NCERT Class 10 Mathematics, Ch 10 "Circles", §10.3_
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