How do you graph #r=theta#?

1 Answer
Feb 28, 2018

The graph is a spiral that starts from the origin of coordinates (when #theta#=0) and unravels counterclockwise.

Explanation:

As #theta# increases from 0 to #pi#/2, the graph moves from the the origin of coordinates counterclockwise, getting farther and farther from it.

It intercepts the Y-axis at point #pi#/2 because, when #theta#=#pi#/2, r=#pi#/2.
Therefore, x=rcos(#theta#)=(#pi#/2)cos(#pi#/2)=0 and y=rsin(#theta#)=(#pi#/2)sin(#pi#/2)=#pi#/2.

Similarly, as #theta# increase to #pi#, the graph intercepts X-axis at #pi#.

Then Y-axis at 3#pi#/2.
Then X-axis at 2#pi# etc.

That's how a spiral form is made.

Do a Google search for "r=theta graph" to see how the graph looks.