Revise trigonometric ratios of sine, cosine and tangent and calculate angles in right-angled triangles with this Bitesize GCSE Maths Edexcel guide.

An equilateral triangle with side lengths of 2 cm can be used to find exact values for the trigonometric ratios of 30° and 60°. The equilateral triangle can be split into two right-angled triangles.

A 3,700-year old Babylonian clay tablet reveals an ancient method of constructing right-angled triangles that makes it the world’s oldest and most accurate trigonometric table.

I'm talking about trigonometry, of course: that bastion of angles and triangles that is essential to calculating velocity, momentum, and much more.

The 3,700-year-old Babylonian tablet known as Plympton 322 turned out to be a trig table, expressed in ratios of the lengths of the sides of the triangles, rather than angles. Credit: UNSW/Andrew ...