Question

fan and medal!
please help, how do i do this question?
https://i.gyazo.com/82745e3c4f75db58ac943428a7b4c534.png

Answer 1

like how do I find the answer

Answer 2

what's the equation for an ellipse?

Answer 3

There is 2, one for each of the two ellipse types right?

Answer 4

yep, what are they?

Answer 5

horizontal is (x-h)^2 / a^2 + (y-k)^2 / b^2 =1
and vertical is (x-2)^2/b^2 + (y-k)^2 / a^2 = 1

Answer 6

and how do you differentiate between the two?

Answer 7

the bottom part of the equation is reversed in the vertical equation

Answer 8

no, I'm saying when do you use horiz and when do you use vert?

Answer 9

I'm not sure on that part, our teacher didn't really give us much to work with

Answer 10

all good. that's what I'm here for!
you use the horizontal equation when the foci are on the left and right. (y=0, x=something)
you use the vertical equation when the foci are above and below (y=something, x=0)
so you know now that you have to use which equation?

Answer 11

I believe vertical?

Answer 12

cool!
now here's what you do with the directrix.
\[y=a^2/c\] is the directrix equation

Answer 13

c is the foci distance from 0.

Answer 14

Not to rush you but I have to pack up and shut down my computer pretty soon and so I did something really quickly and I think I have the answers, I believe it is C?

Answer 15

I'll be another minute, you're close to the answer! and with knowledge of a^2, you plug in 3 for c. a^2=25, a=5.
then to find b, it's b^2 = a^2 – c^2
b^2=25-9=16
b=4
plug in and you're done

Answer 16

b=4
a=5
so it's A
yay!

Answer 17

Thank you !! I understand now

Answer 18

cool! just memorize the equations, it'd tedious but easier understanding-wise than you'd think!