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The radius of the incircle of a triangle whose sides are 9 cm, 12 cm and 15 cm is
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- 9 cm
- 13 cm
- 3 cm
- 6 cm
- 9 cm
Correct Option: C
9² + 12² = 15²
∴ The triangle is right angled
AB = 9, BC = 12 cm
OD = OE = OF = x cm
AD = AF = 9 – x
EC = CF = 12 – x
∴ AC = AF + FC
= 9 – x + 12 – x = 15
⇒ 21– 2x = 15
⇒ 2x = 21 – 15 = 6
| ⇒ x = | = 3 cm. | |
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