What is Law of Cosines?
Law of cosine is the fundamental law of trigonometry the law of cosine is used to find the relation between sides and the angles of the triangle, suppose we are given sides of the triangle and then the angle of the triangle is found. This formula is used to find the unknown angle of the triangle when all sides are given.
Law of Cosines Definition
Law of cosine is defined as the law which gives the relation between sides and angles of the triangle. Three laws of cosine are,
- a2 = b2 + c2 – 2bc cosA
- b2 = c2 + a2 – 2ca cosB
- c2 = a2 + b2 – 2ab cosC
where a, b, and c are the sides of the triangle and A, B, and C are the angles of the triangle.
Law of Cosines
Law of Cosines in Trigonometry 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:
a2 = b2 + c2 – 2bc cos A
Similarly, all other angles B and C are given. In this article, we will learn about, the Law of Cosines, the Law of Cosines formula, examples, and others in detail.
Table of Content
- What is Law of Cosines?
- Law of Cosines Formula
- Law of Cosines Proof
- How to Find Angle using Law of Cosines
- Sine Formula
- Examples Using Law of Cosines