Question

The area of the triangle is 28.7 square centimeters. What is the base length of the triangle in centimeters?

Answer 1

In order to derive the base of a triangle from its area, you need its height as well.

In fact, if we solve the area formula for the base, we have

$A=\dfrac{bh}{2} \iff 2A = bh \iff b=\dfrac{2a}{h}$

So, the base length would be

$b=\dfrac{2\cdot 28.7}{h} = \dfrac{57.4}{h}$

where h is the height relative to the base you're interested in.