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Without using calculator,evaluate Sin15 deg,Cos 15 deg,Sin 75deg. O need the answer urgently pls.

  • Math -

    sin 15°
    = sin(45-30)
    = sin45cos30 - cos45sin30
    = (1/√2)(√3/2) - (1/√2)(1/2)
    = (√3 - 1)/(2√2)

    so cos 15° the same way

    and for the last : sin(75°) = sin(45+30)

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