The Law of Cosines
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Objective
I can solve real-world problems involving triangles by applying the Law of Cosines to determine unknown side lengths or angles.
Part 1 of 3
Warm-up video
Unknown Channel · 5:00
We don't generate video — this one is by Unknown Channel on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.
Part 2 of 3
Practice
7 questions
Explain the Law of Cosines and describe how it differs from the Pythagorean theorem.
Given a triangle with sides B = 10 units, C = 15 units, and an angle θ = 60°, use the Law of Cosines to find the length of side A.
Part 3 of 3
Exit ticket
Quick comprehension check
“A triangle has sides measuring 15 units and 20 units, with an included angle of 60°. Calculate the length of the third side using the Law of Cosines. Show all work. In a triangle, the lengths of two sides are 9 units and 12 units, and the angle between them is 45°. Determine the length of the third side using the Law of Cosines. Show all work. ”
Sample answer included in the free materials
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Teacher Guide
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