The way to find the area of an equilateral triangle is the same as finding the area of other triangles. $$\text{The area of a triangle :}\frac{\text{Base x Base Height}}{2}$$ According to the above formula, we need to know the base and base height . However is it possible to calculate one or the other if we don’t know its value? For example, generally the base (of an equilateral triangle) is known but the base height is not known. The main problem is; can we know the height by using the base value? First of all, let us look at the height of isosceles and equilateral triangles. Let us have a triangle where the base is equal but the arms can be flexible . When both sides are equal then the height is exactly joint together in the middle point. The yellow and blue lengths are equal, the green length, i.e. the height has split the base into two equals as shown. Now our triangle is an isosceles triangle, if the black edge, i.e. the