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

Trigonometry - Edexcel Calculating an angle The three trigonometric ratios; sine, cosine and tangent are used to calculate angles and lengths in right-angled triangles.

It covers elementary trigonometry to the logarithmic solution of triangles, and makes a good beginning by defining the functions of angles of any magnitude with the aid of co-ordinates.

Learn how to find the angles in right-angled triangles with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

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.