equations trig

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8sin^2x+sinxcosx+cos^2x=4

  • equations trig -

    very tricky

    8sin^2x+sinxcosx+cos^2x=4
    8sin^2x+sinxcosx+cos^2x=4(sin^2x + cos^2x)
    8sin^2x+sinxcosx+cos^2x=4sin^2x + 4cos^2x
    4sin^2x + sinxcosx - 3cos^2x = 0
    (sinx + cosx)(4sinx - 3cosx) = 0
    sinx = -cosx or sinx = (3/4)cosx
    sinx/cosx = -1 or sinx/cosx = 3/4
    tanx = -1 or tanx = 3/4
    x = 135°, 315° or x = 36.9° or 216.9°

    if you want radians, change your calculator to rad

  • equations trig -

    thank u very much!

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