Polar coordinates

problem
Polar bearings

Age

16 to 18

Challenge level

What on earth are polar coordinates, and why would you want to use them?
problem
Bent out of shape

Age

14 to 18

Challenge level

An introduction to bond angle geometry.
problem
Polar flower

Age

16 to 18

Challenge level

This polar equation is a quadratic. Plot the graph given by each factor to draw the flower.
problem
Maltese cross

Age

16 to 18

Challenge level

Sketch the graph of $xy(x^2 - y^2) = x^2 + y^2$ consisting of four curves and a single point at the origin. Convert to polar form. Describe the symmetries of the graph.
article
An introduction to polar coordinates

This introduction to polar coordinates describes what is an effective way to specify position. This article explains how to convert between polar and cartesian coordinates and also encourages the creation of some attractive curves from some relatively easy equations.