Find the area of an equilateral triangle of side 10?

Answer 1

First find the perpendicular height (h) of the triangle using Pythagoras.

h = sqrt (102 - 52) = sqrt 75 = 8.660254038...

Now, area of a triangle = 1/2 base x height.

So: area = 1/2 x 10 x 8.660254038 = 43.3 (1 decimal place.)