Answer:
cos theta is -0.866
Step-by-step explanation:
We have the range as between 90 and 180 degrees (pi is the same as 180 degrees)
The quadrant we are considering here is the 2nd quadrant
Mathematically;
if sin theta = 0.5
theta = arc•sin 0.5
theta = 30 degrees
The angle on the second quadrant is of the likes;
180-theta
so we have 180-30
and that is 150 degrees
cos (150) is thus; -0.866
