Answer asap which of the following is equivalent to sin(3pi/4) ? a. sin(- 3pi/4) b. -sin(3pi/4) c. sin(pi/4) d. sin(- pi/4)

The answer is: C. sin(π/4)
To solve this problem you must apply the proccedure shown below:
 1. You have the following expression given in the problem above: sin(3π/4).
 2. Then, the reference angle of 3π/4 is:
 =π-3π/4
 =π/4
 3. Then you have that:
 sinβ=±sinα Where α is the reference angle. Therefore
 sin(3π/4)=±sin(π/4) 
 4. Therefore you choose in you answers options: sin(3π/4)=sin(π/4)