A triangle has sides 13 cm, 14 cm, and 15 cm. Which of the following is its area?

Step-by-step solution

1. Find the semiperimeter: $s=\frac{13+14+15}{2}=21$.
2. Compute $s-a$, $s-b$, $s-c$: $21-13=8$, $21-14=7$, $21-15=6$.
3. Multiply: $21\times 8\times 7\times 6=7056$.
4. Take the square root: $\sqrt{7056}=84$.
5. Thus the area is $84{\text{cm}}^2$.

Concept tested: Area of triangle using Heron's formula

Published 13 October 2026 · How this solution was prepared and checked