>>13248882oh and if you're wondering how I got it
Divide the triangle into 2 right-angled triangles, do the Pythagorean theorem for b and c, put h^2 on one side and now c^2 - x^2 = b^2... bla bla algebra and now you have the formula for x. now just use the Pythagorean theorem in one of the 2 triangles