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Two concentric circles have radii 5 cm and 13 cm. The length of a chord of the larger circle that touches the smaller circle is
A12 cm
B13 cm
C18 cm
D24 cm
Answer & Solution
Correct answer: D. 24 cm
1. The chord is a tangent to the smaller circle; perpendicular from centre = 5 cm.
2. Half-chord squared = 13 squared minus 5 squared = 169 minus 25 = 144.
3. Half-chord = 12; full chord = 24 cm.
_Source: NCERT Class 10 Mathematics, Ch 10 "Circles", §10.3_
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