Answer:
-5/13
Step-by-step explanation:
sin theta = opp / hyp
sin theta = -12 /13
we can find the adj side by using the pythagorean theorem
adj^2 + opp ^2 = hyp^2
adj^2 +(-12)^2 = 13^2
adj^2 +144 =169
adj^2 = 169-144
adj^2 = 25
Taking the square root of each side
adj = ±5
We know that it has to be negative since it is in the third quad
adj = -5
cos theta = adj / hyp
cos theta = -5/13
