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Math Help - Need help verifying trig equations.

  1. #1
    BennyM
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    Need help verifying trig equations.

    How would I verify questions, such as..

    sin x = sin (360° +x)

    cotA * sec˛A * sin˛A = tan A

    (1 + sinA * cosA) (sinA - cosA) = sinłA - cosłA

    cscA = (secA + tanA) / (secA - cosA + tanA)
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by BennyM View Post
    How would I verify questions, such as..

    sin x = sin (360° +x)
    Consider the RHS

    and use the addition formula for sine

    \sin (A + B) = \sin A \cos B + \sin B \cos A

    can you continue?


    cotA * sec˛A * sin˛A = tan A
    Consider the LHS

    change \cot A to \frac {\cos A}{\sin A}

    change \sec^2 A to \frac 1{\cos^2 A}

    can you continue?



    (1 + sinA * cosA) (sinA - cosA) = sinłA - cosłA
    Consider the RHS

    use the formula for the difference of two cubes on \sin^3 A - \cos^3 A to expand it

    difference of two cubes formula: a^3 - b^3 = (a - b) \left( a^2 + ab + b^2 \right)

    can you continue?

    cscA = (secA + tanA) / (secA - cosA + tanA)
    Consider the right hand side

    change \sec A to \frac 1{\cos A}

    change \tan A to \frac {\sin A}{\cos A}

    then combine all the fractions and simplify as much as possible

    can you continue?
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