Question

Calculate the radius of the circumcircle of a triangle, whose sides are given as $5,3$ and $4$ mm respectively.

• A. $2.1$ cm
• B. $2.5$ cm
• C. $2.3$ m
• D. $2.5$ mm

Answer 1

Answer: (D)

$2.5$ mm

Circumcircle of a triangle, radius $=$ $\frac{abc}{4\times \sqrt{s(s-a)(s-b)(s-c)}}$

Where, $s=$ $\frac{a+b+c}{2}$

$s=$ $\frac{5+3+4}{2}$

$s=6$

radius $=$ $\frac{5\times 3\times 4}{4\times \sqrt{6(6-5)(6-3)(6-4)}}$

$=$ $\frac{60}{4\times \sqrt{6\left(1\right)\left(3\right)\left(2\right)}}$

$=$ $\frac{60}{4\times 6}$

$=2.5$ mm

Radius of the circumcircle $=2.5$ mm