…use the ruler to draw another line to complete the triangle and mark a right angle at the point where the two chords meet. You can see that this is a right-angled triangle. If in doubt, imagine ...

The problem begins with a drawing of a small triangle within another bigger triangle. The data available to viewers who want to try and solve the problem is that one angle is 20° and another is 80°.

Learn about angles in triangles and quadrilaterals with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

In a new peer-reviewed study, Ne'Kiya Jackson and Calcea Johnson outlined 10 ways to solve the Pythagorean theorem using trigonometry, including a proof they discovered in high school.