the sides of a triangle are in the ratio 5 : 12 : 13 and its perimeter is 180 m , its area is ?
"5 x + 12 x + 13 x = 180 = > x = 6 a = 30 , b = 72 , c = 78 s = ( 30 + 72 + 78 ) / 2 = 90 answer : a"
multiply(180, divide(180, add(add(5, 12), 13)))