Trigonometry

If sin(x) = 4cos(x), then what is (sin(x))*(cos (x))?

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asked by Katie
  1. if sinx = 4cosx
    sinx/cosx =4
    tanx= 4 = 4/1

    sketch a right-angled triangle with opposite 4 and adjacent 1
    then r^2= 4^2 + 1^2
    r = √17

    then sinx = 4/√17 , cosx = 1/√17

    sinxcosx = (4/√17)(1/√17) = 4/17

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    posted by Reiny

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