Plot[Sin[x], {x, -2 Pi, 2 Pi}, AspectRatio → Automatic]
r Sin[\[Theta]] - Sin[r Cos[\[Theta]]]
If you search the documentation, you will find functions you can use for this.
You can use the documentation either in Mathematica or online at http://reference.wolfram.com/.
I would recommend searching for “Polar” to begin with.
Alternatively, in Mathematica, you can use natural language input. Type Ctrl+= and then enter “Polar Plot of Sine”
If the natural language input doesn’t understand, then I would suggest searching the documentation for “Polar”.
You will find a number of different kinds of polar plots and some examples on how to make them.
