### Maltese Cross

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.

### Polar Bearings

What on earth are polar coordinates, and why would you want to use them?

# Polar Flower

##### Age 16 to 18Challenge Level

Factorise the equation $$r^2 - r + {\textstyle{1\over 4}} \sin^2 4\theta = 0$$ and hence plot the graph given by this polar equation.