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Math Help - Trigonometric identities

  1. #1
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    Trigonometric identities

    Trigonometric identities

    Prove the identity 1-cos2 x= cos2 x tan2 x

    Hint: use t-chart

    Left hand side right hand side
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  2. #2
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    Re: Trigonometric identities

    Attempt?
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  3. #3
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    Re: Trigonometric identities

    The LHS side reduces to sin^2(x), due to the LHS being an offshoot of the Pythagorean Identity sin^2(x)+cos^2(x)=1. The RHS side can be rewritten as cos^2(x)*(sin^2(x)/cos^2(x)), due to the fact that the definition of the tangent ratio is the sine of the angle over the cosine of the angle. The cos^2(x) cancels out, leaving sin^2(x). Since both sides are equal (without crossing the equal sign), the identity has been proven.
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