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what is the exact value of sin^2 pi/6-2 sin pi/6 cos pi/6 +cos^2 (-pi/6)? a) 2- sqrt 3 b) 2- sqrt 3/ 2 c) 2+ sqrt 3/2 d) 2+ sqrt 3 I am not sure how to work this out and would appreciate you how to show me the process. Thank you in advanced!!!!!!!

If cos theta= -sin theta, then sin^2 theta is? a) 1/4 b) 1/2 c) sqrt2/2 d) - sqrt 2/2 please show me how you got the answer! thank you!

what is another form of: sin (A+B) sin (A-B)/ cos^2 A cos^2 B a) cos^2 A - cos^2 B b) tan^2 A - tan^2 B c) tan^2 A - tan^2 B d) sin^2 A - sin^2 B please show the steps you take to get to the answer! thank you