Cosine Rule a2 = b2 + c2 - 2bc cos ∠x b2 = a2 + c2 - 2ac cos ∠y c2 = a2 + b2 - 2ab cos ∠zWhen to use law of sines vs law of cosines?
Depending on the information we have available, we can use the law of sines or the law of cosines. The law of sines relates the length of one side to the sine of its angle and the law of cosines relates the length of two sides of the triangle to their intermediate angle.When to use cosine rule?
The cosine rule is a formula commonly used in trigonometry to determine certain aspects of a non-right triangle when other key parts of that triangle are known or can otherwise be determined.What is the cosine rule?
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.