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Thread: please help

  1. May 18th 2006, 01:13 AM #1
    melissa
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    Question please help

    given that cos0=1/2 and 0 is anacute angle find the value of sin0 using trigonometric
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  2. May 18th 2006, 04:20 AM #2
    topsquark
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    Quote Originally Posted by melissa
    given that cos0=1/2 and 0 is anacute angle find the value of sin0 using trigonometric
    sin^2 \theta + cos^2 \theta = 1

    So
    sin \theta = \pm \sqrt{1- cos^2\theta}=\pm \sqrt{1-(1/2)^2}

    = \pm \sqrt{1-1/4}=\pm \sqrt{3/4} = \pm \sqrt{3}/2.

    We know that theta is an acute angle, so it's in the first quadrant. Also, sine is positive in the first quadrant. Thus: sin \theta= \sqrt{3}/2.

    -Dan
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