Question 590871
sin a/2 = + or - sqrt((1-cosa)/2)
sin pi/12 = + or - sqrt((1-cos pi/6)/2) ........ it becomes pi/6 because the pi/12 is the half angle and we need to substitute the regular angle which is 2x the half angle.
sin pi/12 = + or - sqrt((1-sqrt(3)/2)/2)
sin pi/12 = + or - sqrt((2-sqrt(3)/4)

That is the answer