Respuesta :

mlarsen5000

Answer:

x=21.9317121994

Step-by-step explanation:

You just look at the half triangle and use the Pythagorean Theorem.  One side of the triangle is 9 (half of 18), the other is 20, so you find the hypotenuse.

9²+20²=x²

81+400=x²

481=x²

√481=x

x=21.9317121994