*EDIT* - Solved

God help me...er...you, please.

I need to find out how to solve

(11 * pi) / 8

without using a calculator, and getting the exact value, only knowing the addition, subtraction, double, squares, and half-angle identities, as well as the basic chart for angles 0, 30, 45, 60, and 90 degrees, for all six major trigonometric function.

Please help and please show work, my life depends on it!

THANK YOU mucho in advance!

-Rob DiMarco
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Edit: Well, oops! I did mean sin (11pi/8) but I got it already, thanks anyways!

do you mean sin(11pi/8) cos(11pi/8) ?? 11pi/8 by iteself is just an angle and it is already in simplest form

By using the sum and difference formula:

sin(11pi/8) also = sin (4pi/8 + 7pi/8) = sin(pi/2) * cos (22.5deg) + cos (pi/2) * sin (22.5deg).

Now figuring out the sines and cosines at 22.5deg could be a real hassle, if you want the EXACT VALUE.