Law of cosines

Introduction to the law of cosines to solve for a side of a triangle when 2 sides and an angle are known.

Category:

Education

Tags:

• trigonometry
• math
• law
• of
• cosines

[aphroditesem]

hi im having aproblem with my homework law of cosines heres the given.. a=? c=8 b=12 angle C=38 degrees... im goin to find for side a but the problem is Angle A is not given how can I solve for angle A??? please I need your response..

[khanacademy]

Solve for angle B (either with law of sines or law of cosines), then you will know angle A since A+B+C=180, then you could solve for a.

[opinionhead444]

I like these proofs.

[timmyfasho]

@flowiepanda math of this level is almost all completely arbitrary

[flowiepanda]

8:52 "A year or two from now when you go to college and it's been four years since you took trigonometry..." A year or two... four years... 2 = 4?

[flowiepanda]

you say arbitrary a lot...

[curtknows101]

@horatiohornblowerer Makes your mind do pushups lol lol, im gna learn some of this stuff and may never use it, but with my skills with my hands and tools im really gna look smart when i whoop out some of these words at work, lmaoff, i may be totally wrong but they wont know 8-D

[curtknows101]

So you know im 43, fairly smart in my field of usable knowledge, love to learn, im a mechanic, a carpenter, and basically a jack of all trades, you lost me about 4 minutes in by the way, lol, you probably one of the guys who draw the plans i read to build the things that we all use, buildings, cars, things such as that, back in my days of hs we didnt have the options of algebra or trig, didnt need it, so they say, thumbs up on your vid it is very interesting to see the other side, 8-D

[anonymous345]

Is anyone else watching this because this showed up in multivariable calculus (dot product)?

[soccerbabez45]

I need to know how to solve and draw out diagrams using te formula for law of cosine :(

[DarklightALBANIA]

Yeah now I am writing you notes with a multi color pen.

[Fictionarious]

Thanks Sal, I was embarking into tall calculus 3 grass when a wild geometrical statement appeared! I couldn't catch it until after watching this.