Maths trigonometric

Find the value of sinx ,if 8sinx-cosx=4

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  1. 8sinx-cosx = 4
    8sinx = cosx+4
    64sin^2x = cos^2x + 8cosx + 16
    64-64cos^2x = cos^2x + 8cosx + 16
    65cos^2x + 8cosx - 48 = 0
    (5cosx-4)(13cosx+12) = 0
    cosx = 4/5 or -12/13
    so, sinx = 3/5 or 5/13

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