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    Find, to 1 decimal place, the values of x in the interval −180° ≤ x ≤ 180° for which

    a) cos (x + 40°) = 0.3,
    b) 2 + tan 2x = 0.

    a) cos-1(0.3) will give you the '1st' value of cos. Then you can draw this value onto a quadrant diagram. The interval is -120 ≤ x + 40 ≤ 220.

    Remember cos is positive, so values are in the 1st and 4th quadrants.

    b) tan 2x = -2, -360 ≤ 2x ≤ 360 and then solve like in a)

    Reply back if your still stuck, with the bits you dont understand.
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Updated: April 15, 2006
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