Question

The value of sin (180 + x) is equivalent to... PLEASE EXPLAIN! I have the answer; I just don't know the approach to take. My approach got me the right answer, but I feel as if the approach is wrong.

Answer 1

By the way, my approach was...

180 + x is Quad 3
Sin is negative in quad 3
Thus answer is -sin x

Is that the correct approach?

Answer 2

well use the sum of 2 angles

sin(A + B) = sin(A)cos(B) + cos(A) sin(B)

then let A = 180 and B = x

substitute then you can find the values of sin(180) and cos(180)

then simplify

hope it helps

Answer 3

Sin(180) Cos (x) + Cos (180) Sin (x)
0 * cos(x) + -1 sin x
-1 sin x

Ah got it, thanks!