Law of Cosines Worksheet

Practice applying the Law of Cosines to solve for unknown sides and angles in triangles.

Grade 10 Math TrigonometryLaw of Cosines

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Includes

2 Short AnswerFill in the BlanksMultiple ChoiceTrue / False

Standards

CCSS.MATH.CONTENT.HSG.SRT.D.10

Topics

mathtrigonometrylaw of cosinesgrade 10

7 sections · Free to use · Printable

Law of Cosines Practice

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Read each question carefully and use the Law of Cosines to solve for the unknown side or angle. Round your answers to the nearest tenth.

1. In triangle ABC, a = 10, b = 12, and C = 60°. Find the length of side c.

2. In triangle XYZ, x = 7, y = 9, and z = 5. Find the measure of angle X.

3. The Law of Cosines is used when you know two sides and the angle (SAS), or when you know all sides (SSS) of a triangle.

4. Which of the following formulas represents the Law of Cosines for side 'b'?

b² = a² + c² - 2ac cos(B)

b² = a² + c² + 2ac sin(B)

b = a + c - 2ac cos(B)

b = a² + c² - 2ac cos(B)

5. The Law of Cosines can be used to solve for angles in a right-angled triangle.

True

False