Trig

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Find sin2theta, cos2theta if csctheta=13/12 and lies in quadrant II.
Thank you!

  • Trig -

    If csc Ø = 13/12, the sinØ = 12/13
    so we are dealing with the 12-5-13 right-angled triangle in II
    then cosØ = -5/13

    sin 2Ø = 2sinØcosØ
    = 2(12/13)(-5/13)
    = -120/169

    cos 2Ø = cos^2 Ø - sin^2 Ø
    = 25/169 - 144/169
    = -119/169

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