Question

What is the area of an equalateral triangle of side length x?

Answer 1

First you need to make a line that is perpendicular to one side. The diagram is shown below. then the length of the line that is perpendicular to the triangle is
$\frac{ \sqrt{3}x }{2}$
then the area of the equilateral triangle equals to
$\frac{1}{2} height \times base$
so the area would be
$\frac{ \sqrt{3} {x}^{2} }{4}$