Question

The semi-perimeter 's' of a triangle having sides $\text{12, 9 and 15}$ is ___.

Answer 1

$\text{Semi perimeter, s =}\frac{a+b+c}{2}$,
where a, b and c are the sides of the triangle.
$s=\frac{12+9+15}{2}$
$=\frac{36}{2}=18$