Law of Cosines

How to use the Law of Cosines when you don't have a right triangle to solve for the missing side or missing angle. We discuss how to know when to use the Law of Cosines as opposed to the Law of Sines. We go through 2 examples - one where you are given 3 sides and another where you are given 2 sides and an angle.

0:07 When to Use the Law of Cosines
0:29 3 Different Formulas for the Law of Cosines
1:25 Example 1 Find the Missing Side Length Given SAS
3:17 Example 2 Find the Missing Angle Given 3 Sides

Related Videos:

Law of Sines

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[pirategames]

Thanks a lot! I had a hard time understanding cosine and sine law until i watched this. it cleared a lot of things up!

[fortimusprime]

You are truly talented in teaching! Thank you for helping us students with your teaching! You are THE BEST math teacher I have ever seen!!!

[rameentahir]

I just watched this and now I understand the concept very well, thanks for this video!

[bass]

makes it so much less confusing *sobbing joyfully* thank you so much! 😂👏

[rylieshaesmith]

Thank you so much!! You are a lifesaver! You made me understand this way better!

[brrrayday]

You really sum it up well. This was review for me, have an exam coming up, but you get two thumbs up. Didn't waste time on fluff, and you helped really picture those formulas. If you ever throw a math party, ill bring the beer

[addressunknown]

Great Video!! I learned a lot in a short amount of time

[oscarbadiri]

Thanks a lot, now i understand everything

[davidrange]

This is very helpful! At 5:01 why did you do the inverse of Cos?

[purpledino]

I find an easier Formula for SSS is <A= b^2 + c^2 - a^2 / (2xbxc) the parenthesis are essential. Once you do the formula you take the Inverse Cosine and there’s your answer

[davidm]

That's another good one, and I'm shocked that it garnered so few views.  I'm still voting for the blackboard, maybe with bright colored chalk.  Again, the full screen format of Kahn or the Organic Tutor is very visually engaging -no offense.  Dark colored clothing with your current set-up is indeed a good idea.  Thanks!