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Show that sin(x+pi)=-sinx.

So far, I used the sum formula for sin which is sin(a+b)=sin a cos b+cos a sin b.
sin(x+pi)=sin x cos pi+cos x sin pi
I think I am supposed to do this next, but I am not sure.
sin(x+pi)=sin x cos x+sin pi cos pi
If that is right then I am not sure what to do from there. Can someone please help?

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  1. in(x+pi)=sin x cos pi+cos x sin pi but cosPI=-1, sin PI=0
    sin(x+PI)= -sinx

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    bobpursley
  2. Thanks bobpursley!!!

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  3. Can you please help me with one more?

    Which are simplified forms of the expression tan^2T cos2T? Select all that apply. (2 answers)
    a. 2sin^2T-tan^2T
    b. tan^2T-2cos^2T
    c. 2sin^3T/cosT
    d. cos2T/cot^2T
    e. 2cos^2T-tan^2T

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  4. (sin^2T/cos^2T)(2 cos^2 T - 1)
    = 2 sin^2 T - tan^2 T

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