Can you explain the following question/answer?

Complete each statement:
#sin (180^o - theta)#

1 Answer
Apr 7, 2018

#sin(180-theta)= sin theta#

Explanation:

#sin(180-theta)= sin theta#

Basically, this identity is saying that for any angle in the first and second quadrant, as long as it is a sine, #180-theta=theta#

Another way to think of it is to expand it

#sin(180-theta)#
=#sin180costheta-cos180sintheta#
=#sintheta#