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Law of Cosines: Definition and Application

Instructions:

Choose an answer and hit 'next'. You will receive your score and answers at the end.

question 1 of 3

In the pictured triangle, side a is 9 and side b is 6. If ∠C is 26 degrees, then approximately how long is side c? Round the value of the cosine to 2 decimal places.

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1. In the pictured triangle, side b is 12 and side c is 16. If ∠A is 84 degrees, then approximately how long is side a? Round the value of the cosine to 2 decimal places.

2. In the pictured triangle, side a is 17 and side c is 20. If ∠B is 19 degrees, then approximately how long is side b? Round the value of the cosine to 2 decimal places.

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About This Quiz & Worksheet

The Law of Cosines is important to know when you're dealing with triangles. The quiz will test how well you can determine side lengths and degree measurements using the Law of Cosines.

Quiz & Worksheet Goals

The quiz and worksheet will review:

  • How to use the Law of Sines
  • When to use the Law of Cosines
  • The formula for the Law of Cosines
  • Example problems

Skills Practiced

Use these materials to practice these skills:

  • Problem solving - use acquired knowledge to solve practice problems using the Law of Cosines
  • Making connections - use understanding of the Law of Cosines formula
  • Knowledge application - use your knowledge to answer questions about triangle angles and sides

Additional Learning

If you want to study more, head over to the accompanying lesson titled Law of Cosines: Definition and Application. The lesson will cover the following objectives:

  • Define the Law of Cosines
  • Describe when to use this law and its applications
  • Provide an easy way to remember the formula
  • Review the Pythagorean Theorem and the Law of Sines
  • Show several examples of the Law of Cosines in use
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