# How do you solve a triangle if you are given A= 135 degrees, b = 4, c = 9?

You'd like to use the law of sines because it is simpler. However, in order to use it, you need to know an angle and its opposite side. So you'd need to know $a$.
Use the law of cosines to find $a$. Tlhen you can use that and the law of sines to find $C$.