Converting radians to degrees, help!

  • Thread starter StarkyDee
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  • #1
StarkyDee
I know this is an easy problem, but I need to know 3 sets of polar coordinates for the Cartesian coordinates (-4,4[itex]\sqrt{3}}[/itex])

So I graphed the points and got the hypotenuse, r = 8.

How do I convert 4[itex]\sqrt{3}}[/itex]) to degrees?

(4[itex]\sqrt{3}}[/itex]) = 6.92820 Is this in radians?

and do I then multiply it by (180/pi) to get degrees?

thanks.
 

Answers and Replies

  • #2
Hurkyl
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[itex]4 \sqrt{3}[/itex] isn't an angle...
 
  • #3
chroot
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It sounds like you've already drawn a triangle -- so use trig to solve for the angle. The angle is the inverse tangent of y/x.

Why are you trying to convert the cartesian y-coordinate to degrees? That doesn't even make sense.

- Warren
 
  • #4
StarkyDee
Ah. Inverse Tan of y/x.

4[itex]\sqrt{3}}[/itex]/-4 = -1.7320 = -60 degrees.

Thanks ~Dave~
 
  • #5
Hurkyl
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Don't forget to check that your answer is in the correct quadrant!
 
  • #6
StarkyDee
well -60 degrees would be in the 4th quadrant.
but when i graph (-4,4[itex]\sqrt{3}}[/itex]) it is only valid in the 2nd quadrant and you can't have a -60 degrees in the 2nd quad. so if i start in the 4 quadrant at -60

the 3 points would be: (8,-60);
add 360 (8,-240);
opposite angle (8,120). is this correct?

thanks again!
 
  • #7
Hurkyl
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Well, tell me, how many of those are in the second quadrant?

All of your answers must be in the second quadrant because the desired point is in the second quadrant...
 
  • #8
StarkyDee
Ah. So -60 would not work because it's in the 4th quadrant. therefore (8,-60) is not a point. that makes sense.

but (8,-240) and (8,120) and (8,-600) would be in the 2nd quadrant.
 
  • #9
Hurkyl
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right.
 
  • #10
StarkyDee
Thanks for helping me out Hurkyl, appreciated much!
Studying for finals have turned my brain into mush.
 

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