A triangle with sides of 25 cm, 52 cm, and 63 cm has a second triangle drawn inside it with all its sides at a distance of 3 cm from the sides of the original triangle. Find the area of the inner triangle.

Triangle => ABC inner triangle => A'B'C'

s = 1/2(25+52+63) = 70

A = 630 cm^{2}

r = A / s = 9

Similarity coefficient = (r - 3) / r => 6/9 = 2/3

[A'B'C'] = A * (2/3)^{2} = 630 * (4/9) = 280