1. Honors Geometry Section 10.5 Law of Cosines

2. In section 10.4, we learned how to use the Law of Sines to solve a non-right triangle. The Law of Sines will not help us in the next problem however.

3. Solve the triangle. Round to the nearest 1000 th as necessary. Note: In order to use the Law of Sines, you must know an angle and the side opposite it.

4. The Law of Cosines will help us solve this type of triangle.

5. Law of Cosines

6. Use the Law of Cosines to solve the triangle in the example above.

7. Solve the triangle. Round to the nearest 1000 th as necessary. NOTE: When applying the Law of Cosines to a triangle where only the three sides are known, find the largest angle first ( i.e. the angle _____________________. opposite the longest side

8. Solve the triangle. Round to the nearest 1000 th as necessary.