In any isosceles triangle ABC with AB = AC, the altitude AD bisects the base BC so that BD = DC. If AB = AC = 25 and BC = 18, then determine the length of the altitude .
A
B D C
AD = sqrt [ AB^2 - [ (1/2)BC ] ^2 ] = sqrt [ 25^2 - 9^2 ] = sqrt [ 625 - 81 ] =
sqrt [ 544 ] ≈ 23.32
