SOLUTION: What's the exact value of sin 13π/12 without using a calculator ? Can you please show all your work Thanks

Algebra ->  Trigonometry-basics -> SOLUTION: What's the exact value of sin 13π/12 without using a calculator ? Can you please show all your work Thanks       Log On


   

Question 577832: What's the exact value of sin 13π/12 without using a calculator ? Can you please show all your work Thanks
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
13pi/12 = pi + pi/12 --> 3rd Quad
sin(13pi/12) = -sin(pi/12)
In degs, = -sin(15)
--------------
Use the half-angle formula
= -sin(30/2)
-sin(15) = -sin(30/2)
= -sqrt%28%281+-+cos%2830%29%29%2F2%29
= -sqrt%28%281+-+sqrt%283%29%2F2%29%2F2%29
= -sqrt%282+-+sqrt%283%29%29%2F2