Foci of a hyperbola | Conic sections | Algebra II | Khan Academy

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  • Опубліковано 16 гру 2024

КОМЕНТАРІ • 47

  • @neilsklar3509
    @neilsklar3509 4 роки тому +12

    Sal is a truly gifted teacher, but this isn't one of his better lessons. The frequency with which he starts and then abandons sentences mid-stream here makes for a very fragmented learning experience.

  • @jandy608
    @jandy608 2 роки тому +2

    For me, when I'm using the formula for an ellipse, I tend to not use the variables a and b as "horizontal" or "vertical" radii. I would rather just say that the variable a represents the major radius instead of whatever the horizontal radius is. Same for b, I tend to use that as the shorter radius (minor). I think this is just an easier way or referring to these radii when I'm using the formula for an ellipse to find the foci/focal distance

  • @nycscuba11
    @nycscuba11 13 років тому +2

    To determine which way they Hyperbola opens can be simplified by saying whenx^2 is proceeded by a plus sign it is horizontal or When y^2 is proceeded by a plus sign the transverse axis is vertical. Or even simpler which ever is written first being the plus one is always written first in standard form.
    Very helpful video

  • @payasitopimpim2002
    @payasitopimpim2002 15 років тому +2

    thanks for all... khanacademy .....your useful lessons .....from lima peru

  • @e1ghtSpace
    @e1ghtSpace 7 років тому +4

    13:46 Oh thank god, I was like "Aww man, I have everything backwards."

  • @inuyome1008
    @inuyome1008 14 років тому +3

    I do love his voice.

  • @Chordinated
    @Chordinated 12 років тому +2

    i was tought that no matter what a>b. a is always the semi major axis and b is always the semi minor axis. i'm sure either works but i find it interested that both ways are tought, i'm sure this has lead to some confusion

  • @DanielRamirez-uc4kl
    @DanielRamirez-uc4kl 11 років тому +10

    The whole video: was useless to me until 12:40

    • @phancakes6219
      @phancakes6219 3 роки тому

      Right? At least 12 minutes wasted....

  • @InternetSandman
    @InternetSandman 3 роки тому +1

    the alarm going off in the background really kept making me take my headphones off cause I thought it was from my own room lol

  • @ThatsJustLardy
    @ThatsJustLardy 11 років тому +9

    dang. thought it was folk-eye

    • @wedeldylan
      @wedeldylan 7 років тому

      You can say it either way ua-cam.com/video/wLjMLBNkPN0/v-deo.html

  • @readthesecomments
    @readthesecomments 15 років тому +1

    i think you should make videos about how to be as cool as you

  • @kiwilimepi1
    @kiwilimepi1 12 років тому +5

    How would you find the vertices?

    • @nononnomonohjghdgdshrsrhsjgd
      @nononnomonohjghdgdshrsrhsjgd 3 роки тому

      if you put y to zero, you will get the smallest absolute (positive and negative) value of x, which is the vertex by 0 shifting. It is the smallest value, because of the minus sign between x squared and y squared in the equation. if you put instead y to zero, you will get for hyperbola around the x axis complex rooots resp. there are no real roots, therefore there is no intersection with y axis of real numbers.

  • @farhannajme7542
    @farhannajme7542 8 років тому +1

    Thank you so much

  • @noncanadian
    @noncanadian 12 років тому +2

    i dont even remember this conversation its been so long, don't dig up old comments and annoy people please...

  • @silencedidgood
    @silencedidgood 15 років тому

    How can you produce videos longer than 10 minutes for You Tube? I'm lovin having one spot to both look at the math of kinematics and the Paulson plan!

  • @jonnachi
    @jonnachi 13 років тому

    If we are graphing and we got the foci from the a^2-b^2=c^2.. Do I count from the vertex of the hyperbola or from the center to graph?

  • @noncanadian
    @noncanadian 13 років тому

    @454ffv
    it appears you need to polish up those math skills of yours kind sir
    (it could be y=[4/2.5]x though)

  • @aeropostale4277
    @aeropostale4277 14 років тому

    how do you know which one is a or b? is it always under one axis?

    • @onlyme0101
      @onlyme0101 2 роки тому

      a to x and b to y axis

  • @khoembunnamath2738
    @khoembunnamath2738 6 років тому

    can you explain me
    about directrix of
    hyperbola.

    • @ssn90
      @ssn90 5 років тому

      Does hyperbola even have a directrix??

    • @sanyamjain7058
      @sanyamjain7058 5 років тому

      @@ssn90 yes ofcourse

  • @CH1EFBL1TZ
    @CH1EFBL1TZ 14 років тому

    at 13:05 he messed up. Hyperbola is minus not plus between the x squared and y squared

    • @belogical2396
      @belogical2396 4 роки тому

      Li Jimmy your repied on a 8 yo comment

  • @454ffv
    @454ffv 13 років тому

    at 14:00 wouldnt the line be y=4/3x?

  • @ReganQuinn
    @ReganQuinn 11 років тому +1

    i am still struggling wiht finding the solution to a Hyperbola in standard form... and finding the foci and verticies!

  • @je.dansky
    @je.dansky 13 років тому

    ...fair enough.

  • @shanesantos5396
    @shanesantos5396 8 років тому +9

    They're teaching us these things (and more) in tenth grade. I feel like it's too advanced. Gosh, math, why you do dis to me?!

    • @hhaze2020
      @hhaze2020 5 років тому +1

      WTH we are never even taught conic section in Alevel,just gotta learn this shiote for college entry tests

  • @noncanadian
    @noncanadian 13 років тому

    @454ffv
    meant to say y=[4/2.25]x... doesn't change the fact that you're still wrong... (you said) 4/3 =1.3 | (i said) 4/2.25 =1.7(repeating) | (he said) 16/9 =1.7(repeating)... Get It? Good! Get Out House!

  • @cardboardpox
    @cardboardpox 13 років тому +1

    is anyone else cramming for tomorrow's finals?

  • @aeropostale4277
    @aeropostale4277 14 років тому +2

    this is confusing ):

  • @brennano1487
    @brennano1487 8 років тому +1

    where the fuck is the volume?

  • @evelyngamez6819
    @evelyngamez6819 4 роки тому

    it looks like gibberish

  • @nikkikali9507
    @nikkikali9507 7 років тому +2

    I thought this was going to help me learn to find the foci in a hyperbola. But it doesn't! If your going to make a video about hyperbolas, then don't talk about ellipses.

    • @TsukikoKutamora
      @TsukikoKutamora 7 років тому

      Nikki Kali I was looking for the same thing

    • @nikkikali9507
      @nikkikali9507 7 років тому

      Tsukiko Kutamora were you able to find the foci from this video?

    • @TsukikoKutamora
      @TsukikoKutamora 7 років тому

      Nikki Kali I didn't

  • @HEMANTYADAV-xp6pt
    @HEMANTYADAV-xp6pt 6 років тому

    Bad

  • @NotLegato
    @NotLegato 8 років тому +1

    you are really struggling with your wording here. when making educational videos for the whole world, you oughta at least practice the ones you struggle with.