Check the picture below.
so if we just find the vertex of that parabolic path, we'd get how far up it went and how long it took


well, as you see in the picture, the horse hits the ground again when h(t) = 0

so at t=0 and t=1 it's touching the ground, at t=0 when it begins to jump at t=1 when it thumps back down, took that long.