Respuesta :

AnimeBrainly
Remember SOCAHTOA

In this case, you are using Cos, or CAH

Cos = adjacent/hypotenuse

You are using B as your starting point. 

The adjacent of B is a, while the hypotenuse (the longest side) is c

a/c = cos, and should be your answer


hope this helps
BrainAxe
cosine is adjacent over hypotenuse, so the answer is a/c. hope that helps!