Find the area with Heron's Formula
semi-perimeter = 17
Area = sqrt [ 17 * 2 * 7 * 8 ] = 4sqrt 119
The shortest altitude is drawn to the longest side....so....
4sqrt119 = (1/2) 15 * altitude
altitude = 4/ 7.5 * sqrt 119 = 4 / (15/2) * sqrt 119 = (8/15)sqrt 119