Law of Cosines Worksheet
Practice applying the Law of Cosines to solve for unknown sides and angles in triangles.
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Law of Cosines Practice
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Read each question carefully and use the Law of Cosines to find the missing side or angle. Round your answers to two decimal places.
1. In triangle ABC, a = 10, c = 12, and angle B = 60°. Find the length of side b.
2. A triangle has sides of length p = 7 cm, q = 9 cm, and the angle between them is R = 85°. Find the length of side r.
3. In triangle XYZ, x = 5, y = 8, and z = 10. Find the measure of angle X.
4. A triangular garden has sides of length 15 ft, 20 ft, and 25 ft. Find the measure of the largest angle in the garden.
5. Which formula represents the Law of Cosines for finding side 'a'?
a² = b² + c² - 2bc sin(A)
a² = b² + c² - 2bc cos(A)
a / sin(A) = b / sin(B)
a² + b² = c²