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A circle is inscribed in a triangle of sides 8 cm, 10 cm and 12 cm. The radius of the inscribed circle if the area is 15 (square root of 7) sq cm equals
A2 cm
B(square root of 7) cm
C3 cm
D(15 square root of 7)/15 cm
Answer & Solution
Correct answer: B. (square root of 7) cm
1. Semi-perimeter s = (8 + 10 + 12)/2 = 15 cm.
2. r = Area/s.
3. r = 15 (square root of 7)/15 = (square root of 7) cm.
_Source: NCERT Class 10 Mathematics, Ch 10 "Circles", §10.3_
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