SSC CHSL 2023 PYQ — Question 69

The correct answer is option 3 i.e. $\frac{27\sqrt{5}}{10}$.

a = 12 cm, b = 9 cm, c = 9 cm

Semi-perimeter formula is (s) = (a + b + c)/2 = (12 + 9 + 9)/2 = 30/2 = 15 cm

Area = √[s(s - a)(s - b)(s - c)]

= √[15(15 - 12)(15 - 9)(15 - 9)]

= √[15 × 3 × 6 × 6]

= 18√5 cm²

Circumradius (R) = abc/[4 × Area of the triangle]

= (12 × 9 × 9)/(4 × 18√5)

= 972/(72√5)

= (27√5)/10

Therefore, the circumradius of the triangle is (27√5)/10 cm.