Cosine Rule a2 = b2 + c2 - 2bc cos ∠x b2 = a2 + c2 - 2ac cos ∠y c2 = a2 + b2 - 2ab cos ∠zWhen to use law of cosines?
When to Use. The Law of Cosines is useful for finding: the third side of a triangle when we know two sides and the angle between them (like the example above) the angles of a triangle when we know all three sides (as in the following example)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 formula for cosine?
Cosine Formula. Cosine Formula is normally used to calculate the angle of the right triangle. It is the relation between the angles and sides of the right triangle. Cosine Formula is the trigonometry ratio of the adjacent side to the hypotenuse side of the right triangle. Cosine is a periodic and even function and sometimes shortened as 'cos'.