Question

A=77 deg, B=42 deg, c=9

how do i set this up in the laws of sines or cosines to find length of sides
i think i may have done this wrong on my previous problems.

Answer 1

I believe you can use the law of sines
a/sinA=c/sinC

Angle C = 180-77-42=71 degrees

Answer 2

a/sin 77 = 9/sin 71 degrees.

That should do it. Solve for a, you will then have two sides all three angles, only have side b to figure out. Use law of sines again.