An equilateral triangle with side length 18 cm is shown in the diagram, work out the height of the triangle.

MathsMia
Apr 18, 2017

#1**+1 **

There are a couple of ways to do this......but.....if we divide the triangle in half with a vertical line, we will have a right triangle with one leg = 9 and the hypotenuse =18.....and the height will form the other leg

Using the Pythagorean Theorem the height, H =

sqrt ( 18^2 - 9^2) = sqrt (243) = sqrt (81 * 3) = 9 sqrt(3) cm

CPhill
Apr 18, 2017