Use the Law of Cosines when the length of one side and the measure of any two angle are known in an oblique triangle, to find the measure of the other angle or the length of the other two sides.

Question

Quizplus · Accepted Answer

The Law of Cosines is used when you know either all three sides of a triangle or two sides and the included angle. To find an unknown angle when you know one side and two angles, you would typically use the Law of Sines.

Use the Law of Cosines When the Length of One