# Spherical Polar coordinate geometric diagram

Discussion in 'Physics' started by logearav, Mar 13, 2012.

1. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Revered members,
I have attached the image i.e geometric construction for spherical polar coordinate. I understand r(x,y,z) is at the distance r from the origin and r is the position vector of the point r from the origin. $\Phi$ is the azimuth angle. I want to know why we draw vertical line from the point r. Also what is the need for another line similar to r in the xy plane. I have denoted both these lines using red colour.

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2. ### evilclem Member

Dec 20, 2011
118
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The main purpose I can see is that they help to illustrate the location of point r relative to the x,y axis.

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3. ### steveb Senior Member

Jul 3, 2008
2,433
469
It also provides the basis for measuring the angle $\phi$ . You need to make a projection of the point into the xy-plane to define this angle.

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