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.

Trigonometry close trigonometryThe study of sides and angles in triangles. can be used to find a missing side in a right-angled triangle when another side and an angle are known. An understanding ...

Matt Parker. Riverhead, $30 (336p) ISBN 978-0-593-41810-9 “We all rely on triangles to keep our modern world ticking along,” according to this disappointing paean.

According to the researchers, Plimpton 322 is a trig table, similar to the ones seen in every high school math textbook, except Plimpton 322 uses triangles instead of circles and angles.