Use compound angle formulas to evaluate

Question

a) cos(pi/12)

b) sin(pi/12)

c) tan(5pi/12)

d) sin(11pi/12)

Answer 1

just apply the half-angle formulas.
Post your work if you get stuck.

Answer 2

for the first one i got [sqrt(2)(1+sqrt(3))]/4 . can i simplify this further?

Answer 3

not really. I might say
(1+√3)/√8 or (1+√3)/(2√2)