The Cosine Rule (1 of 3: Proof of the Formula)

[magulongchannel]

I really don't like Math, but Mr. Woo's teaching caught my attention and sparked my interest in the subject. Not only this, he also seemed to capture my heart bit by bit the more I watch him. Lol!

Kidding aside, the way he teaches here is perfectly clear and easy to understand. Impressive teaching. Your students and the school where you are teaching are lucky to have such a brilliant mind like you.

[AriaHarmony]

12:48 Pythagorean Theorem: Enhanced Edition now available on all consoles! err.. triangles! lol
Your videos are helping me understand math much much better, especially trig. You're the best teacher ever! Thank you very much! <3

[jds]

wow that was awesome to watch. I can't believe this is actually interesting to me i used to hate math

[arcelbengco]

Nice technique in showing the formula of law of cosines. However, in the part of your video 12:30-12:37; why do you need to swap b to c? Students in other institution may get confuse with that.

Instead of replacing b to c, why not let b^2 be transpose on the left side of the equal sign and let the formula be like this:

b^2=a^2+c^2- 2ac (cos B)
In that case, there will be no confusion among students at the same time there will no more question, why "b replaced c."

Because replacing b to c is illogical. Why not stop there and arrange everything as I have shown.

[enock]

those 2 dislikes probably thought that was a download icon hahahaha

[PS-tdmj]

sometimes i feel like he's something out of a Japanese anime

[eipimath]

Thanks for sharing! I posted a short video on deriving the law of cosines, It should apply for all angles (acute, obtuse, reflex, negative). Hope to get your thoughts.

[Consistencyaday]

You a great teacher but I am still confused

[briankelly]

Eddie - you should be making videos for 'The Great Courses' series from America.

[umamahobeidullah]

why did he first switch the places of c and b?

[Ensign_Cthulhu]

11:06 I lose track of how he justifies this.