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    Sin2A -1 = Cos2A
    Well im stuck
    Sin2A - 1 = 1 -2 Sin^2 A
    Turning it into a quadratic won't work here since Sin2A = f(2x) .
    Please advice
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    Use sin 2A = 2sinAcosA

    You'll have a quadratic in sin A.
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    (Original post by Bilbao)
    Sin2A -1 = Cos2A
    Well im stuck
    Sin2A - 1 = 1 -2 Sin^2 A
    Turning it into a quadratic won't work here since Sin2A = f(2x) .
    Please advice
    \sin(2A) - \cos (2A) = 1 which is 2\sin A \cos A - \cos^2 A + \sin^2 A = \cos^2 A + \sin^2 A

    This then reduces nicely.
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    (Original post by BobbJo)
    Use sin 2A = 2sinAcosA

    You'll have a quadratic in sin A.
    What do i do with the cosA?
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    (Original post by RDKGames)
    \sin(2A) - \cos (2A) = 1 which is 2\sin A \cos A - \cos^2 A + \sin^2 A = \cos^2 A + \sin^2 A

    This then reduces nicely.
    Ok ill try that
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    (Original post by Bilbao)
    What do i do with the cosA?
    You could write cos 2A = cos^2 A - sin^2 A instead, then use 1=sin^2 A + cos^2 A, the next step will become apparent
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    (Original post by Bilbao)
    Sin2A -1 = Cos2A
    Well im stuck
    Sin2A - 1 = 1 -2 Sin^2 A
    Turning it into a quadratic won't work here since Sin2A = f(2x) .
    Please advice
    Dear Student you can proceed as follows.
    Sin2A-1 = 2Cos^2 (A) -1
    2Cos^2(A) -Sin2A = 0
    2 Cos^2(A) - 2SinACosA = 0
    2CosA(CosA-SinA) = 0
    Either CosA = 0 or CosA - SinA = 0
    A = InvCos(o) or TanA = 0
    A = InvTan(0)
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    (Original post by Bilbao)
    Sin2A -1 = Cos2A
    Well im stuck
    Sin2A - 1 = 1 -2 Sin^2 A
    Turning it into a quadratic won't work here since Sin2A = f(2x) .
    Please advice

    (Original post by Bilbao)
    Sin2A -1 = Cos2A
    Well im stuck
    Sin2A - 1 = 1 -2 Sin^2 A
    Turning it into a quadratic won't work here since Sin2A = f(2x) .
    Please advice
    Dear Student you can proceed as follows.
    Sin2A-1 = 2Cos^2 (A) -1
    2Cos^2(A) -Sin2A = 0
    2 Cos^2(A) - 2SinACosA = 0
    2CosA(CosA-SinA) = 0
    Either CosA = 0 or CosA - SinA = 0
    A = InvCos(o) or TanA = 0
    A = InvTan(0)
 
 
 
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