NDA 2025 Maths · Mathematics · Properties of Triangles · medium

Its circumradius is

Single correct option

The sides of a triangle are

13

14

and

15

. Its circumradius is

Show answer and solution

Answer: (D) $\dfrac{65}{8}$

Semi-perimeter

s=21

, area

=\sqrt{21\cdot8\cdot7\cdot6}=84

. Then

R=\frac{abc}{4\Delta}=\frac{2730}{336}=\frac{65}{8}

. The inradius would be

\Delta/s=4

;

7

is half the middle side, a common guess.

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