A circle is inscribed in a right-angled triangle whose perpendicular sides are 9 cm and 12 cm. Find the radius of the inscribed circle.

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Accepted Answer

1. Find the hypotenuse: $c=\sqrt{9^2+12^2}=\sqrt{225}=15$. 
2. Area of triangle: $A=	frac{1}{2}	imes9	imes12=54$. 
3. Semiperimeter: $s=	frac{9+12+15}{2}=18$. 
4. Inradius: $r=\dfrac{A}{s}=\dfrac{54}{18}=3$. So **radius = 3 cm**.

FINAL_ANSWER: b

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