To solve problems involving non-right-angled triangles, the correct rule must first be chosen. The cosine rule can be used in any triangle to calculate: a side when two sides and the angle in between ...

The mathematical study of triangles has just got a whole lot simpler, according to a researcher who says his new theory of trigonometry is easier to use and more accurate. Associate Professor Norman ...

a missing side in a right-angled triangle when another side and an angle are known. a missing angle in a right-angled triangle when two sides are known. In these formulae, the Greek letter θ (theta) ...