There’s a delightful mathematical moment in the movie Merry Andrew, when Danny Kaye, playing schoolmaster Andrew Larabee, breaks into song to teach the Pythagorean theorem. I was reminded of this ...

The sides of right-angled triangles are labelled opposite, hypotenuse and adjacent. Trigonometry explores the relationship between sides and angles in right-angled triangles. The hypotenuse is the ...