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Pre-Calc

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find the exact value of sin(-15pi/6) and cot(-7pi/6)

  • Pre-Calc -

    Perhaps you can "think" better in degrees than radians, sometimes I can.
    sin(-15π/6)
    = sin(-450°)
    = sin(-90) , I took away one rotation
    = -sin(90°) = -1

    cot (-7π/6)
    = cot(-210°)
    = cot(150°) , 150 and -210 are coterminal
    = - cot(30°) , 150 is in II and by CAST rule cotangent is negative, and 30° from the x-axis
    = -1/tan 30°
    = -1/(1/√3) = -√3

  • Pre-Calc -

    Thank youu(:

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