Foci of an Ellipse

[Pastariceboy]

thank you so much i was sick from school, and i bet this is better than what i would have learned!

[TheSpyker123]

Sal what do you get out of this? I mean superman gets lois lane batman gets a cool car what do you get for saving millions of children's futures

[deewahhht]

Thanks. My final Extension maths exam is in 3 days and this helped heaps!

[lkrauss100]

I think you're wrong when you say a>b means that it's horizontal. it's horizontal if the x value is over the a value, and not the y value

[blake81088]

@lkrauss100 You're right. A is always greater than B...what determines the shape is the location of the A and B values (A under X = wide and short, A under Y = tall and skinny). Good work.

[toriatong]

OMG thanks u sooooo much!!! u r a genius!!!

[sophaura]

So helpful!

[moj543]

thank you so much.... i finally understand ellipses now!

[Benjikj]

can you do a video on the proof of the Focal/Optical Property for ellipses, thanks

[Benjikj]

can you do a video on the proof of the foca/optical property!!

[Itshardtopronuncius]

so pumped for the math test tomorrow!

[Sylvanas17]

THANK YOU!!!!!!!!!! UR AWESOME!!!

[GenericCoder]

Really interesting video thanks alot great explanations.

[MilitantBlackGuy1]

Fosi sounds wierd, I pronounce it Foki, afterall you don't say fosus in singular form. Great vid though..

[Lavabug]

Nice, it would be cool if you discussed on Kepler's laws of planetary motion with this!

[mrinehart93]

Thanks so much for this video! I had a takehome quiz today, and the way you explained this was so much better than the way my teacher explained it. This really helped a ton. Keep up the good work!

[photographerj2]

so, in a nut shell, if the center of a horizontal ellipse is (h,k), the foci are (h+the square root of a^2+b^2, k) and (h-the square root of a^2+b^2, k). Is this correct??? thanks for the help.

[ItsNeuroscience]

I don't understand, why do you have to say "(one plus the square root of 5, -2)"? When finding the vertices(of the major axis), shouldn't you just be able to count, in this case, plus or minus two along the x-axis from the center of the ellipse? Thus, making the vertices of this ellipse (3, -2) & (-1, -2)? Why the square root of 5? Why add the foci if it just represents a point of focus for each parabola???

[AtheistSense]

Well you didn't prove that the sum is true for any point on the ellipse though...

[lphuff]

I'm a teacher and I am very interested in what program you are using to make this video. I thank you in advance.

[raxtar107]

thanks.. this really helps!!!!!!!

[simpleplan15]

well said...this helps me a lot in advance studies that my teacher requires us to do...^^

[deathvlife]

Right now, I'm learning pure math 30 online (grade 12 smart math), and this was such a HUGE help, 5 starts all the way, you really know your stuff and could explain it very well.

[Xx0Mystic0xX]

Thx alot! BTW Is a vertical shaped ellipse different? How would you find the coordinates of the foci of that?

[saedar1]

you suppose to use capital letters for points

like F

instead of f

for focus

[darkcross117]

omg ty so much! Now i understand a lot clearer on how to use a and b in order 2 find my vertices n co-vertices a lot faster.

[maddiexmcg]

honestly how many more times can you say d1 + d2 = 2a

[johnr1031]

i still dont fucking know how to do my homework ahh!!!

[gillsmcgee411]

this guy's a great teacher

[Thrash505]

Thanks so much, I finally understand ellipses now. I previously was confused on how the Pythagorean Theorem applied here. My text just kept modifying the formula for each type of problem and not telling why, so instead I had to memorize when to use each variation of the formula and what numbers to plug into it. Now I can figure out which variation to use myself.

(wish you'd use a dry-eraser board or something though... or get a cheap tablet pc so you can draw directly on the screen...)

[kitsuneswordsman]

Thanks so much man... my textbook doesn't teach me what's necessary to solve the problems given(they are lousy textbooks!), but you helped me! lol you're like a living textbook. Again, thanks!

[joshlete]

Is "a" always the semi major radius, for example if you switch the denominators 9 and 4(vertical ellipse), would "a" still be 3 or would it be 2?

[porchiges]

man you are the best. this takes my teacher like half an hour to explain plus its so boring i fall asleep. thank you so much

[Gearmasher1]

you may have just saved me from failing my test on monday! Thank you so much!

[horizon956]

Thank you very much (:

[Bryan2394]

Thanks

[anyclassical]

good!

[blakeobeans]

btw, this is the law of planetary motion that Kepler used to prove that the earth revolved around the sun.

[torkg]

I think the f1 point at the end should be [ (sqrt(5)-1, -2 ]. I might be wrong. Great vid btw

[KruZer7]

Mr. Khan, is awesome.

[vkgoku2012]

Your using a drawing pad what happen to scroll bar.

[jhonma1]

Thanks for the explanation

[newazninvasion]

very well explained

[Skygerobrian]

average of 4.5 stars... wtf who didnt give 5 to this guy wtf

[Cobija13]

so glad this stuff is done. thanks to you, i partially understood my final lol

[thomals]

you go over the same things too many times.

love the vids though, man.

[MustNotRead]

no he doesn't

[phillywilly66234]

everything is able practice and also he is just going through all possible scenarios.