Circle theorems are properties that are true for all circles, regardless of their size. There are six theorems to learn and recognise. Questions can have a combination of theorems. It is important to ...

You might be surprised to learn that you can’t comb the hairs flat on a coconut without creating a cowlick. Perhaps even more surprising, this silly claim with an even sillier name, the “hairy ball ...

Many prominent phenomena originate from geometrical effects rather than from local physics. For example, the 'hairy ball' (HB) theorem asserts that a hairy sphere cannot be combed without introducing ...