 # Apply Law of Cosines

Video lessons, examples and solutions to help High School students learn how to understand and apply the Law of Sines and the Law of Cosines to find unknown measurements in right and non-right triangles (e.g., surveying problems, resultant forces).

Common Core: HSG-SRT.D.11

The Law of Cosines
This video introduces the law of cosines and solve triangles using the law of cosines.

The requirements for solving oblique triangles using the Law of Cosines are
SAS: Two sides and an included angle are known
SSS: Three sides are known.

Law of Cosines, Example 1
This video gives the formula for the Law of Cosines and use it to find the missing side length of a triangle.

Law of Cosines, Example 2
This video gives the formula for the Law of Cosines and use it to find the missing side length of a triangle.

The Law of Cosines applications
This video solves applications using the law of cosines.

Example 1: Application of the Law of Cosines
This video determines the width of a lake using the law of cosines.

Example 2: Application of the Law of Cosines
This video determines the distance a plane has traveled after a change in direction.

Example 3: Application of the Law of Cosines
This video determine the length of a diagonal of a parallelogram using the law of cosines.

Resultant Forces using law of sines and cosines
vectors using law of sines and cosines.

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.  