Lets say triangle A is similar to triangle B… A has sides a,b,c, and height h B has corresponding sides d,e,f, and height g Area of A = (1/2)(a)(h) Area of B = (1/2)(d)(g) There is a scale factor s that relates a to d, b to e, c to f, and h to g a = s*d b = s*e c = s*f h = s*g So area of A can be re-written as