Math
posted by Anonymous .
Evaluate
*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)

11 is 5 + 6
7 is 12 + 5
5 is 2 3
13 is 2 + 11, and 11 is above.
Watch the algebra. 
5 and 6 over what?
They have to either be over 3, 4, 6, or 2.