Question

The difference between the semi perimeter and the sides of a triangle ABC are 8 cm ,7 cm,5 cm. Find its semi perimeter?

Answer 1

We know, $2s=a+b+c$, where $s$ is the semi-perimeter of $\Delta ABC$.
We are given,
$s-a=8 \\ s-b=7 \\ s-c=5$.
Add all these equations, you get $3s-(a+b+c)=8+7+5 \Rightarrow s=20$.

Answer 2

Answer is given by -