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)
