1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Negative of Polar Coordinates

  1. Nov 6, 2014 #1

    Say I have a variable 'x' which has the polar value 10@-75°, would '-x' be -10@+75° or 10@+75° as I am a touch confused as to which bit I have to invert
  2. jcsd
  3. Nov 6, 2014 #2
    The notation "-x" usually refers to the additive inverse of x. That is, we want x + (-x) = 0. Therefore, if you are using the usual Euclidean notion of vector addition (the parallelogram law, equivalent to the addition of Cartesian components), you must find the polar components of the vector whose addition to x will yield the additive identity: the 0 vector. In the vectors of Euclidean geometry, this is the vector that points in opposite direction to x, but with equal magnitude. Thus, it is the reflection of x through the origin (if one attaches the tail of x to the origin). Attached is an example of the geometric viewpoint. Do you see which vector that should be for your particular case ? After you find it geometrically, then you would find its polar components.
    Of course, if you are using a different notion of vector addition, then your result will vary. In that case, you would have to describe the context of your application.

    Attached Files:

    Last edited: Nov 6, 2014
  4. Nov 6, 2014 #3


    User Avatar
    Science Advisor

    In polar coordinates x and -x have the same magnitude and have angles which differ by 180 deg. In your example -x is 10@105 deg.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Negative of Polar Coordinates