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Math Help - Simple double angle formulae

  1. #1
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    Simple double angle formulae

    Hi,

    Can someone please show me how to answer this question:

    Solve 2sin^2x = sin2x, 0<x<pi


    Thanks!

    p.s I know its simple, but I'm stuck for some reason..
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by CSG18 View Post
    Hi,

    Can someone please show me how to answer this question:

    Solve 2sin^2x = sin2x, 0<x<pi


    Thanks!

    p.s I know its simple, but I'm stuck for some reason..
    Hi CSG18,

    2 \sin^2 x=\sin 2x

    2 \sin^2 x = 2 \sin x \cos x

    2\sin^2 x-2\sin x \cos x = 0

    2\sin x(\sin x - \cos x)=0

    r\:\: \sin x - \cos x=0" alt="2\sin x=0 \:\r\:\: \sin x - \cos x=0" />

    r\:\: \sin x = \cos x" alt="\sin x=0 \:\r\:\: \sin x = \cos x" />

    r \:\:\boxed{x=\frac{\pi}{4}}" alt="\boxed{x=0} \:\r \:\:\boxed{x=\frac{\pi}{4}}" />
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