Law of Cosine

[mauricioliborio]

That is one of THE most important formulas for the 2 D analysis.

Great job, professor

[CNoahDavis]

That is extremely useful. I can use it! 😊

[mahikannakiham]

For those who don't understand where the law of cosine comes from. Take any triangle, divide it into 2 right triangles, then you can easily derive the law of cosine from that. It's a nice exercice to do.

[prashantpurohit]

That's the same calculation in vector, not sure about which one is the original,
btw, a simple trick for prime number i found out,
that every prime number is in the form of 6n+ 1 or 6n +5, if any number doesn't fit in this, it's not prime number, so to check, take any number and divide it to 6, if reminder is 1 or 5, then it's prime number, otherwise not

[souvikmondal]

C²=a² + b²+ 2abcosx
The formula
It's useful to find the third side when the triangle is non right angle

[MathOrient]

We have the line of sines, cosines, and tangents etc :D

[ryanmahadeo]

Thats a short answer, i taught the calculations would be take up the entire chalkboard.... Cool tho.

[gabaryon]

I don't remember ever studying this formula this way, I mean the final psrt of the formula. If I want to study more about this should I just search for law of cosine?

[rizzmechanics]

Whats the reason we sometimes use + instead of that -

[abidomar]

Why +or -? It is length. All time positive

[tectedy]

y(length from B to A) = sin(40.3°) x 3.56 miles this is much easier