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

Discusses the properties and types of triangles, explaining that a triangle is a closed figure with three sides and angles. It categorizes triangles into equilateral, isosceles, scalene, obtuse ...

So equilateral triangles are constructible with a compass and straightedge, QED. Congratulations on persisting through the first proposition in the first book of Euclid’s Elements.

Using such an equilateral triangle in the Vitruvian Man drawing helps produce a specific ratio – 1.64 – between the size of the square and the circle in the artwork.

This large, nearly equilateral triangle is composed of three of the brightest stars in the sky, each belonging to its own constellation.

Henry Dudeney, a self-taught English mathematician and puzzle columnist, asked his readers to dissect an equilateral triangle into the smallest number of pieces that could be rearranged into a square.

A point lies inside an equilateral triangle. If you know the distance of the point from each of the three vertices, what is the side of the triangle?

Pascal’s triangle is a never-ending equilateral triangle of numbers that follow a rule of adding the two numbers above to get the number below. Two of the sides are “all 1's” and because the ...