The Law of Sines - Formula, Examples & Proof - [2-20-7]

In this lesson, you will learn about the law of sines, which we will also prove in this lesson. We will also solve several example problems which will illustrate how to set up the problem, label the angles, and calculate the answer using the law of sines. We also show how to decide when to use the law of cosines instead of the law of sines.

[jeffplunkett]

Thank you for including the proof. As an inquisitive person, I rarely accept things merely on face value; I like to know why it's correct. The beauty of a proof using general variables is there's never a need to re-prove it each time. No need to reinvent the wheel!

[stjohn]

I've been following you for a while now and all I can say is thankyou for sharing your gift to the world. You are truly amazing...

[travisgann]

I'm studying for my level 2 survey technician test and it has a lot of coordinate geometry and nothings/eastings, inversing... a lot of math and you just made it so clear and easy. No longer just memorizing formulas now I can visualize it with a "why" behind the "what" thank you!!!

[ashrafulalam]

Hi Sir
You are the best teacher I have seen !! Appreciated

[AdityaMishra-gdvb]

Sir I am waiting for calculus that you would start from very basics .
Thankyou sir.

[simpleman]

I love this. I was hoping you posted this one. Thank You.

[felixyongco]

Very, very clear Professor Jason..

Thanks..

[SYL-nqyo]

I used to dislike Math, but I enjoyed SINE LAW. THANKS SIR

[hemarajue]

I think there is one more way to derive the sine law, dividing the triangle into two right triangles and equating their heights.

[sabham]

Why in my calculator sin of 25 comes 0, 422 how you find it 0, 423