Answer:
x = 2
Explanation:
The picture helps.
the line is an altitude. It is found with the Pythagorean Theorem.
hypotenuse^2 = x^2 + (8/2)^2
hypotenuse = sqrt(20)
8/2 = 4
sqrt(20)^2 = x^2 + 4^2
20 = x^2 + 16 Subtract 16 from both sides
20 - 16 = x^2
4 = x^2 Take the square root of both sides
sqrt(4) = sqrt(x^2)
x = 2