trig

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Use a half-angle formula to find the exact value of cos 5ð/12

  • trig -

    your symbol for pi did not come out, just type pi, that seems to be the simplest way.

    A lot of students seem to find it easier to think in degrees,
    5pi/12 = 75º
    cos(5pi/12) radians
    = cos 75º
    = cos(45 + 30)
    = cos45cos30 - sin45sin30
    = (√2/2)(√3/2) - √2/2)(1/2)
    = (√6 - √2)/4

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