Question

Mid-points of the sides AB and AC of $\Delta ABC$ are $(3,5)$ and $(-3,-3)$, respectively, then find the length of BC.

Answer 1

Let $D=(3,5),E=(-3.-3),$ then
$DE=\sqrt{(3+3{)}^2+(5+3{)}^2}$
$=\sqrt{36+64}$
$=\sqrt{100}=10$
$\Rightarrow BC=2DE=2\times 10=20$ units