Question

Why do we need to multiply the area by 2 to find the missing side length?

Answer 1

Since the area of the triangle is given by:

$A=\frac{1}{2}bh$

To find the missing length we need to multiply both sides of the equation by 2, this gives us:

$2A=bh$

That's why we need to multiply the area by two, since we are looking at a triangle.