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Trig

posted by on .

The angle 2x lies in the fourth quadrant such that cos2x=8/17.

1.Which quadrant contains angle x?
2. What is the measure of x, in radians?

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I know that angle 2x is in quadrant 4, but quadrant x...? I am not sure where it is and how to get the measure of it in radians.

  • Trig - ,

    Half of quadrant 4 is half of 270deg to 360 deg, or 135 to 190 deg, quadrant 2.

  • Trig - ,

    switch your calculator to radians
    enter
    8
    ÷
    17
    =
    to get .470588...
    press 2ndF, then cos
    to get 1.08084
    This would be the radian measure in the first quadrant, but you are in the fourth,
    so 2pi - 1.0804 = 5.20235
    but this is 2x
    so x = 5.20235/2
    = 2.60117
    (in degrees that would be 149.04º which is in compliance with what bobpursley told you above)

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