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Posted by on Sunday, May 31, 2009 at 12:05pm.

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?

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 - , Sunday, May 31, 2009 at 12:10pm

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

  • Trig - , Sunday, May 31, 2009 at 12:57pm

    switch your calculator to radians
    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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