Answer:
16
Step-by-step explanation:
We can use the Pythagorean theorem to find the height
a^2 + b^2 = c^2 with a and b legs and c the hypotenuse
The triangle is a right triangle with legs GH and FG and hypotenuse FH
FG^2 + GH^2 = FH^2
FG ^2 + 12^2 = 20^2
FG^2 +144 = 400
Subtract 144 from each side
FG^2 +144-144 = 400-144
FG^2 =256
Take the square root of each side
sqrt(FG^2) =sqrt(256)
FG = 16
