Learn about three trigonometric ratios in similar right-angled triangles with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

The course of work in the book is suitable for elementary students of trigonometry, and constitutes an introduction to the theory of functions as illustrated by trigonometrical ratios.

Geometry is another crucial section, with an emphasis on Triangles, Circles, and Areas Related to Circles. Basic concepts of Trigonometry, including Introduction and Applications, are essential.