Main content
Course: Precalculus > Unit 2
Lesson 5: Law of cosinesProof of the law of cosines
Sal gives a simple proof of the Law of cosines. Created by Sal Khan.
Want to join the conversation?
No posts yet.
If you're seeing this message, it means we're having trouble loading external resources on our website.
If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.