Question 1043084
To this "tutor" "ikleyn":  Go back to school.  At the minimum, there is such a thing as Internet.  Here are some references for you.

https://cosmolearning.org/video-lectures/graphing-polar-equations-r25-thetapi3/


https://mathway.com/popular-problems/Precalculus/407122


http://cims.nyu.edu/~kiryl/Precalculus/Section_8.2-Graphs%20of%20Polar%20Equations/Graphs%20of%20Polar%20Equations.pdf


And please DO NOT say those graphs look the way they do because the values of {{{theta}}} are positive!

--------------------------------------------------------------------------


If the polar equation is devoid of the other variable, it means that the absent variable is free to take on ANY real value.  The polar 
coordinates (r,{{{theta}}}) imply that, if {{{theta = -pi/2}}}, then {{{-infinity < r < infinity}}}, and hence the graph is the entire {{{highlight(y-axis)}}}.  In rectangular coordinates, it would be {{{highlight(x = 0)}}}.

(This is much like in rectangular coordinates, where, if you have, for example, x = 5, then the graph is the vertical line with x-intercept 
(5,0), meaning, y was free to vary over all real numbers.)