Question

how do i find the foci of an elipse?

Answer 1

do you know where the center and vertexes are?

Answer 2

if so, then the foci are an odd construction of the usual pythag thrm ...

in this case, b and c are legs, and a is a hypotenus giving us a rather strange look of

c^2 + b^2 = a^2, such that x is the distance from center to focus

Answer 3

well the equation i have is
(x+2)^2/9+(y-4)^2/36=1

Answer 4

then we know a^2 and b^2, right?

Answer 5

yes

Answer 6

so show me c^2 :)

Answer 7

36+ =9
c^2=25

Answer 8

-25

Answer 9

36 - 9 = 27

Answer 10

oh yeah lol

Answer 11

so 3cbrt3 = c, or this distance from center.

Answer 12

3 sqrt3 lol

Answer 13

so, tell me our center, and in what direction we need to move

Answer 14

center (-2,4) we move left and right

Answer 15

not left and right

notice that under y is bigger than under x

y is bigger than x, so our focuses are going to be in relation to y

Answer 16

so (-2, 4+ or - 3sqrt3)

Answer 17

yes

Answer 18

alright

Answer 19

thanks:)

Answer 20

youre welcome

Answer 21

can you help me with one other thing

Answer 22

depends on what it is and how good my memory is :)

Answer 23

finding the eccentricity of (x+7)^/16+(y-3)^2/4=1

Answer 24

define the formula for eccentricity

Answer 25

eccentricity = c/a

Answer 26

thats what i thought

so sqrt(c^2/a^2) should work ..

c^2 is the difference of the bottoms, and a^2 is the larger of them

Answer 27

So sqrt 12/4

Answer 28

um, 16 is bigger than 4

Answer 29

because sqrt 16 is 4

Answer 30

oh, youve got some notation off then

sqrt(12/16)

sqrt(3/4)

sqrt(3)/2

Answer 31

Wait I dont get how you reduced those? wouldnt it just be sqrt(3/4)

Answer 32

Like why did you reduce so far?

Answer 33

thats what you do with fractions, you reduce them till they have no common factors

Answer 34

makes sense.

Answer 35

So final answer is sqrt (3/2)

Answer 36

\[\sqrt{\frac{16-4}{16}}\]
\[\sqrt{\frac{12}{16}}\]
\[\sqrt{\frac{4*3}{4*4}}\]
\[\sqrt{\frac{3}{4}}\]
\[\frac{\sqrt3}{\sqrt4}\]

Answer 37

then reduce? or

Answer 38

can it be simplified more?

Answer 39

i just showed you some of the process, i didnt finish it ... i figured youd be cognizant enough to see where its going.

Answer 40

yea sqr t4 is equal to 2

Answer 41

then lets go with sqrt(3) /2

Answer 42

Then you have sqrt(3/2) :) thanks

Answer 43

no, not sqrt (3/2)

im not sure if its a typing error of yours, or if you are making a mistake. it is:

sqrt(3)
------
2

Answer 44

sqrt(3) sqrt(3)
----- = -----
sqrt(4) 2

Answer 45

yeah thats how I percieved it and meant it

Answer 46

good luck :)