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.

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