Answer:

Step-by-step explanation:
A parallelogram is a quadrilateral with two pairs of parallel sides. Opposite sides of a parallelogram are equal.
Therefore, set any two opposite sides equal to each other to solve for
:
Ok so basically.... 15^2= 9^2+ x^2
15*15
225= 81+x
-81. -81
144=x^2
12=X
Im pretty sure it’s right!
I used the formula A^2+B^2=C^2