Cosine rule: Master the Cosine Rule

Master the Cosine Rule . Learn when to use it (SAS or SSS triangles) for finding unknown sides and angles, with step-by-step examples. Law of Cosines is the fundamental law of mathematics used to find the angle of the triangle when all three sides of the triangle are given. This law is also called the Cosine Rule Or the Cosine Formula . If in a triangle the sides are a, b, and c, then law of cosine for angle A is given as: The cosine rule , also known as the law of cosines, relates all 3 sides of a triangle with an angle of a triangle. It is most useful for solving for missing information in a triangle. For example, if all three sides of the triangle are known, the cosine rule allows one to find any of the angle measures. Similarly, if two sides and the angle between them is known, the cosine rule allows … The law of cosines (or cosine rule ) relates the lengths of the sides of a triangle to the cosine of one of its angles. It can be used to solve triangles when some sides and angles are known, and has various proofs and applications in trigonometry, geometry, and physics.