Pre-Calculus

Hi, I need a bit of help with verifying identities. The problems are as follows:

sinx+cosx/cotx+1=sinx
sin2x/sin - cos2x/cosx=secx
1-tan^2θ/1+tan^2θ=cos2θ

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  1. sin x + cos x / cos x/sin x +1 = ?
    sin x + sin x + 1 = sin x no way
    maybe you mean
    (sinx+cosx)/ (cotx+1)
    (sin x + cos x) / (cos x/sin x + sin x/sin x)
    sin x ( sin x + cos x) / (cos x + sin x)
    = sin x yes
    Parentheses are VITAL !!!!!

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    Damon
  2. sin2x/sin - cos2x/cosx
    = 2sinx cosx/sinx - (1-2sin^2x)/cosx
    = 2cosx - secx + 2sin^2x/cosx
    = (2cos^2x+2sin^2x)/cosx - secx
    see if you can finish it from here

    1-tan^2θ/1+tan^2θ
    = (1-(sec^2θ - 1)/sec^2θ
    = (2 - sec^2θ)/sec^2θ
    see if you can finish it off from here.

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