# QA – Placement Quizzes | Mensuration 2D | Question 14

The sides of a triangle are 6 cm, 11 cm and 15 cm. The radius of its in-circle is:**(A)** 3*(2)^0.5**(B)** (4/5)*(2)^0.5**(C)** (5/4)*(2)^0.5**(D)** 6*(2)^0.5**Answer:** **(C)****Explanation:** Let a, b, c be the sides of the triangle. Then, we know

Semi-perimeter = 1/2 * (a + b + c) = 1/2 * (6 + 11 + 15) = 16 cm.

Area = [s*(s-a)*(s-b)*(s-c)]^0.5 = [16*10*5*1]^0.5 = 20(2)^0.5 cm^2.

Therefore, Radius of in-circle = Area/Semi-perimeter = 20(2)^0.5 / 16 = (5/4)*(2)^0.5 cm.

Quiz of this Question

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