Answer:
Explanation:
First we'll simplify this using the Sum Identity for sin(x + y) where
and y = x. Notice we have 2 of those so we simplify first into
and divide away the 2 on the left to get
and now we'll expand:
and go to your unit circle to find the sin and cos of
and fill in where they go:
(-1cosx + 0sinx) = -1 which simplifies to
-1cosx = -1 so
cosx = 1 and
x = 0 or 2π, depending upon what your interval is.