Before starting this lesson you should already be familiar witht he following.
An equilateral triangle is just a triangle for which all three sides are of equal length. E.g.
Given a triangle's base and height, finding the area of the triangle should be a familar calculation.
Given a right triangle, you should be familiar with the relationship between its sides and its hypotenuse.
For review, check out this lesson on the pythagorean theorem.
Given an equilateral triangle with side length s, the formula for the area of that triangle is
If this is our triangle
then s = 4 so that the area is
(√3 X 42)/4 =
√3 X 4 =
Using the Pythagorean formula and the standard triangle area formula, the formula for the area of an equilateral triangle is derived.
Source: youtube.com, Colin O'Keefe