trig

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using the trigonometric identities find the exact (radical form) value of cos (105 degrees)

  • trig -

    cos 105°
    = cos(60+45)
    = cos60cos45 - sin60sin45
    = (1/2)(√2/2) - (√3/2)(√2/2)
    = (√2 - √6)/4

  • trig -

    cos195

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