三角形面積問題

Let the other 2 sides of the right -angled triangle be a and b.
So, ab/2 = 25 or ab = 50..............(1)
a^ + b^2 = h^2...........................(2)
p = a + b + h..............................(3)
From (3)
(p-h)^2 = (a + b)^2
p^2 + h^2 - 2ph = a^ 2 + b^2 + 2ab.
p^2 - 2ph + h^2 = h^2 + 100 [from (1) and (2)]
p^2 - 100 = 2ph
So h = (p^2 - 100)/2p.