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The length of a tangent from a point at distance c from the centre of a circle of radius r is
Asquare root of (c squared - r squared)
Bsquare root of (c squared + r squared)
Cc - r
Dc + r
Answer & Solution
Correct answer: A. square root of (c squared - r squared)
1. Right triangle formed by tangent, radius and line to centre.
2. Tangent squared + radius squared = c squared.
3. Tangent = square root of (c squared - r squared).
_Source: NCERT Class 10 Mathematics, Ch 10 "Circles", §10.3_
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