Babynini
  • Babynini
Ellipses
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
chestercat
  • chestercat
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
Babynini
  • Babynini
1 Attachment
Babynini
  • Babynini
@freckles
Babynini
  • Babynini
@rational

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Babynini
  • Babynini
oh I know where I calculated wrong. in that c/a and forgot that a was =4 and not 2
Babynini
  • Babynini
would it be b^2 = 2?
Babynini
  • Babynini
nope that's not right either.
Babynini
  • Babynini
@rvc do you know how to do these?
Babynini
  • Babynini
@jim_thompson5910
rvc
  • rvc
bad at circle and conics sorry :(
Babynini
  • Babynini
Thanks for looking at it though. Ah well.
rvc
  • rvc
@divu.mkr help please :)
Babynini
  • Babynini
first off we find a from the major axis a= 4 then we find c by looking at the eccentricity c/a = sq7/2
anonymous
  • anonymous
focii on y axis means that the major axis is on Y aix and you are given with the length of major axis and ecc.. you can find minor axis from that data
anonymous
  • anonymous
axis**
alekos
  • alekos
It would have a vertical major axis so (x-h)^2/b^2 + (y-k)^2/a^2 =1 where 2b=8
Babynini
  • Babynini
how do I find the minor axis in there?
alekos
  • alekos
eccentricity = sqrt(a^2-b^2)/a
anonymous
  • anonymous
b^2 = a^2(1-e^2)
alekos
  • alekos
so from this you can find the minor axis
Babynini
  • Babynini
hmm
alekos
  • alekos
focii are on the y-axis so h=0
Babynini
  • Babynini
so x^2/8 + y^2/16 = 1
Babynini
  • Babynini
is that the answer?
Babynini
  • Babynini
@iambatman save me. lol
anonymous
  • anonymous
Hollllllaaaa
Babynini
  • Babynini
aloo
anonymous
  • anonymous
major axis = 8 ye?
Babynini
  • Babynini
I just need to find an equation :P
Babynini
  • Babynini
yeah
Babynini
  • Babynini
major axis = 2a so a = 4
anonymous
  • anonymous
Yes good :P \[e = \frac{ c }{ a } ~~~\text{and}~~~ c^2 = a^2-b^2\] yes yes this looks good, it will work out nicely
anonymous
  • anonymous
Ok so notice we're given the eccentricity (e) and it tells us the Foci is on the y - axis, this is important because the foci are ALWAYS on the major axis. So will the major axis run vertically or horizontally?
Babynini
  • Babynini
vertically?
anonymous
  • anonymous
That sounds good, so what should we do next
anonymous
  • anonymous
You should already realize an error in your work with that information
Babynini
  • Babynini
a should be the bigger one?
anonymous
  • anonymous
You're too good :)
Babynini
  • Babynini
Aw, shucks.
Babynini
  • Babynini
so what numbers do i flip around?
anonymous
  • anonymous
Well lets find b first
anonymous
  • anonymous
To do that we have \[e = \frac{ c }{ a }\] and \[c^2 = a^2 - b^2\]
Babynini
  • Babynini
e = sq7/2 but we're given that a = 4 so do we double that whole thing?
anonymous
  • anonymous
What was that cute game we were playing earlier? I had a name for it
Babynini
  • Babynini
lol substitution?
anonymous
  • anonymous
Yeah that's it ;)
Babynini
  • Babynini
but we're given the e!
anonymous
  • anonymous
So what's stopping you from solving for c :)
Babynini
  • Babynini
no b?
anonymous
  • anonymous
We have a and e!
Babynini
  • Babynini
ooh oh
Babynini
  • Babynini
sq7/2=c/4
anonymous
  • anonymous
:))))
anonymous
  • anonymous
So what will be our c value?
Babynini
  • Babynini
sq14?
Babynini
  • Babynini
\[2\sqrt{7}\]
anonymous
  • anonymous
Looks good, now what's our next step :)
Babynini
  • Babynini
find b!
anonymous
  • anonymous
Right, and how will we do that
Babynini
  • Babynini
so that's just c, not c^2
anonymous
  • anonymous
Yes good observation!
Babynini
  • Babynini
so now c^2=a^2+b^2
anonymous
  • anonymous
Stop right there for a second!
Babynini
  • Babynini
o.o yes sir.
anonymous
  • anonymous
Lets look at the equation you said, what is that for :)
Babynini
  • Babynini
c
anonymous
  • anonymous
ircle
Babynini
  • Babynini
lol
anonymous
  • anonymous
That's where a lot of people make mistakes, for an ellipse it's \[c^2 = a^2 - b^2\]
anonymous
  • anonymous
Note the negative sign
Babynini
  • Babynini
o.o gasp. that is no bueno.
Babynini
  • Babynini
b^2=a^2-c^2 then
anonymous
  • anonymous
:), now remember as I always say it's a game of substitution
Babynini
  • Babynini
\[b^2 = 16 - (2\sqrt{7})^2\]
Babynini
  • Babynini
\[b^2 = 16-28\] \[b^2=-12\]
Babynini
  • Babynini
\[b=\sqrt{12}\]
anonymous
  • anonymous
No, the negative is there, something is wrong
anonymous
  • anonymous
Err, \[e = \frac{ c }{ a } \implies c = e \times a \implies c = \frac{ \sqrt{7} }{ 4 } \times 4 \implies \sqrt{7}\] bleh :)
Babynini
  • Babynini
..oh hehe
anonymous
  • anonymous
I guess I should be doing the math as well haha
Babynini
  • Babynini
sorry!
Babynini
  • Babynini
ai ai ai I need to go to bed soon. waay to early on a school night =.= and you do too.
anonymous
  • anonymous
No it's alright we just had mistaken the eccentricity we had sqrt(7)/2 when it's 4 :P
Babynini
  • Babynini
oh xD
anonymous
  • anonymous
Don't worry about me :), I'm the dark knight, night is where I work muahah!
Babynini
  • Babynini
right, right, how could I forget!
anonymous
  • anonymous
Alright so lets find b again bleh :)
anonymous
  • anonymous
\[b^2 = a^2-c^2\]
anonymous
  • anonymous
\[a = 4~~~c = \sqrt{7}\]
Babynini
  • Babynini
b = 3
Babynini
  • Babynini
b^2 = 9
anonymous
  • anonymous
Now that looks good
Babynini
  • Babynini
so..the answer I had at the very beginning. Look at the screenshot thing =.=
anonymous
  • anonymous
major axis runs vertically :P
Babynini
  • Babynini
ooh myy goooshh aspidghpaihgpi
Babynini
  • Babynini
fricken hour later hahahah
anonymous
  • anonymous
It's ok, the struggle is more important than the final answer, you will remember how to do it now :)
Babynini
  • Babynini
we're geniuses! :)
Babynini
  • Babynini
for sure though!
anonymous
  • anonymous
Not me, you are a genius! You deserve a fields medal hehe!
Babynini
  • Babynini
noo no bro the answers wrong still D:
anonymous
  • anonymous
What did you put
Babynini
  • Babynini
1 Attachment
anonymous
  • anonymous
Nope.
anonymous
  • anonymous
a = 4, a^2 = 16
Babynini
  • Babynini
...can you write out the whole answer just so i make sure to put it right?
anonymous
  • anonymous
and y runs vertically hence \[\frac{ x^2 }{ 9 }+ \frac{ y^2 }{ 16 } = 1\]
Babynini
  • Babynini
That little green mark though :')
1 Attachment
anonymous
  • anonymous
Yes, sorry about that I did not check if you put a^2
Babynini
  • Babynini
it's all good :) so it was indeed my first answer just forgot to ^2 the a
anonymous
  • anonymous
Yes, we just had to switch it around, but in a test you would have to show your work, and you now know how to do that! :) It's a game of substitution as always!
Babynini
  • Babynini
haha cuz we hate the players (not really) but love the game ;)
Babynini
  • Babynini
yes indeed!
Babynini
  • Babynini
*hug hug hug. you are a trooper. haha and with that. I am off to bed.
anonymous
  • anonymous
Take care :)
Babynini
  • Babynini
Night, Batman.

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