Evaluate

Question

*Note - We have to find the exact value of these. That I know to do. For example sin5π/12 will be broken into sin (π/6) + (π/4)

So...
sin 5π/12
sin (π/6) + (π/4)
sin π/6 cos π/4 + cos π/6 sin π/4

I get all those steps. The part I am struggling with is breaking these into 2 simple ones.

a) sin 11π/12
b) cos 13π/12
c) tan (-7π/12)
d) tan (-5π/12)

Answer 1

11 is 5 + 6

-7 is -12 + 5
-5 is -2 -3
13 is 2 + 11, and 11 is above.

Watch the algebra.

Answer 2

5 and 6 over what?

They have to either be over 3, 4, 6, or 2.