Find the value of x. (hint: use a trigonometric ratio or what you know about the lengths of sides in special right triangles.)

Since all triangles have a sum of 180° and this is a right triangle with a 90 and a 45.  The other angle must be 45.  Since the side opposite the 45 is 9 units long, and the x is opposite the same angle it must also have a length of 9 units.

x=9