Question

How do you find the foci of an ellipse.

Answer 1

(plus/minus a*e,0) where e is the eccentricity (sqrt(1-b^2/a^2)) for an ellipse in standard position.

Answer 2

a(times)e?

Answer 3

Yes

Answer 4

Can I have an example??

Answer 5

Make up your own...:-)

Answer 6

... Please?

Answer 7

You bring me the ellipse, I will show you how to plug the numbers in....

Answer 8

Okay, vertical ellipse center at origin, spaces to the sides 6, spaces vertically - 10

Answer 9

=10*

Answer 10

Work with that.

Answer 11

No, you are supposed to do the work, not me.....

Bring me an equation (and in standard form)

Answer 12

Fine.

Answer 13

Give me a sec.

Answer 14

(x^2/36)+(y^2/100)=1

Answer 15

I think that that is standard.

Answer 16

That is not in standard position....

Answer 17

I'm not too good at this.

Answer 18

What is?

Answer 19

(x^2/100)+(y^2/36)=1

Let's do this one, do you know what a and b are?

Answer 20

Yes.
a=10 and b=6

Answer 21

eccentricity (sqrt(1- b^2/a^2)) ?

Answer 22

(sqrt(1-36)/100)

Answer 23

sqrt(35)/100

Answer 24

Right?

Answer 25

(sqrt(1- b^2/a^2)) One minus .........

Answer 26

-35*

Answer 27

isqrt(35)/100

Answer 28

i*sqrt(35)/100

Answer 29

1 - (36/100) = 64/100 and sqrt is 0.8

Answer 30

How does it equal 64/100?

Answer 31

1 = 100/100 and if you take away 36/100 you get 64/100

Answer 32

Oh!

Answer 33

Okay, I read the perentheses wrong.

Answer 34

So now we have e = 0.8 (it's always between 0 and 1)

Answer 35

Yep.

Answer 36

foci (plus/minus a*e,0)?

Answer 37

+/-(10*.8,0)

Answer 38

Done.

Answer 39

So then we have +/-8,0

Answer 40

Right?

Answer 41

yup

Answer 42

So those are the foci?!

Answer 43

:D

Answer 44

Yes!

Answer 45

Thanks!

Answer 46

2 MEdals then I guess.
lol

Answer 47

ur welcome....(careful when a is less than b, that's an ellipse stood on end)

Answer 48

I know.

Answer 49

Wait.

Answer 50

Does a change in the essentricity?

Answer 51

Does "a" change to b?

Answer 52

If b is grater?

Answer 53

That's an exercise for the reader.....:-)

Answer 54

lol

Answer 55

:-)