3. Geometry and Trigonometry

Cosine Rule — Quiz

Test your understanding of cosine rule with 5 practice questions.

Practice Questions

Question 1

What is the cosine rule for a triangle with sides $a$, $b$, and $c$, where $c$ is opposite the angle $C$?

Question 2

In a triangle, $a = 5$, $b = 7$, and the included angle $C = 60^\circ$. What is $c^2$?

Question 3

Which situation is a good reason to use the cosine rule?

Question 4

A triangle has sides $a = 8$, $b = 6$, and $c = 10$. What is the value of $\cos C$ if $c$ is opposite angle $C$?

Question 5

What happens to the cosine rule when the angle $C$ is $90^\circ$?