Answer:
1st option because those angles are a linear pair.
It cant be converted into a mixed number because it has no whole.
15) factor out cos: cos(x)(sin(x)+1)=0
Now this is true when either cos(x)=0 (x=pi/2 and 3pi/2)
Or when sin(x)=-1 (x=3pi/2)
So it's solutions are pi/2 and 3pi/2
