Trigonometry can be used to find the length of a side in a triangle. Trigonometry close trigonometryThe study of sides and angles in triangles. can be used to find a missing side in a right-angled ...

Named for Plato, who theorized that the classical elements were made of these regular polyhedrons, three of the Platonic solids are composed of equilateral triangles: the tetrahedron, octahedron, and ...