Question

The altitude of an equilateral triangle is 9 meters, what is the side length?

Answer 1

$h=9=\dfrac{a\sqrt3}{2}\\ \dfrac{a\sqrt3}{2}=9\\ a\sqrt3=18\\ a=\dfrac{18}{\sqrt3}\\ a=\dfrac{18\sqrt3}{3}\\ a=6\sqrt3$