SOLUTION: Find the foci, eccentricity, length of latus rectum, and the x and y intercepts of the ellipse x^2/4 + y^2/16=1.

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Find the foci, eccentricity, length of latus rectum, and the x and y intercepts of the ellipse x^2/4 + y^2/16=1.      Log On


   



Question 1112231: Find the foci, eccentricity, length of latus rectum, and the x and y intercepts of the ellipse x^2/4 + y^2/16=1.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
For a wider-than-tall ellipse with center at (h,+k), having vertices a units to either side of the center and foci c units to either side of the center, the ellipse equation is:

%28x-h%29%5E2%2Fa%5E2+%2B+%28y-k%29%5E2%2Fb%5E2=1
For a taller-than-wide ellipse with center at (h,+k), having vertices a units above and below the center and foci c+units above and below the center, the ellipse equation is:
(y-h)^2/a^2 + (x-k)^2/b^2=1

The length of the semi-major axis is a, a "semi-minor" axis is b, the length of the whole major axis is 2a,the length of the whole minor axis is 2b, and the distance between the foci is 2c.
The three letters a, b, and b are related by the equation b%5E2+=+a%5E2+-+c%5E2 .
you are given:
x%5E2%2F4+%2B+y%5E2%2F16=1 or +y%5E2%2F16+%2Bx%5E2%2F4+=1

you also see that a%5E2=16-> a=4 and b%5E2=4-> b=2
as you can see, h=0 and k=0; so, the center of your ellipse is at origin (00)

now we can find the foci, eccentricity, length of latus rectum, and the x and y intercepts:
center is at: (h, k)
(0, 0)
focus is the fixed value c
(0,c) and (0,-c)
use b%5E2+=+a%5E2+-+c%5E2 to find c
+c%5E2=a%5E2+-b%5E2+
+c%5E2=16+-4
+c%5E2=+12+
+c%5E2=4%2A3+
+c=+sqrt%284%2A3%29+
+c=+2sqrt%283%29%29+ or +c=+-2sqrt%283%29%29+
so, foci is at:
(0, 2sqrt%283%29) and (0, -2sqrt%283%29)
vertices at: (0, -a) and (0, a)
(0, -4) and (0, 4)
covertices at: (b, 0) and (-b, 0)
(2, 0) and (-2, 0)
eccentricity is denoted as e+=+c%2Fa
which is
e=+2sqrt%283%29%2F4
e=+sqrt%283%29%2F2
0.866025
length of latus rectum: LR=2b%5E2%2Fa=> LR=%282%2A4%29%2F4=2
x-intercept: set y=0
x%5E2%2F4+%2B+0%5E2%2F16=1
x%5E2%2F4+=1
x%5E2+=4
x+=2 or x+=-2
x-intercepts are at (2, 0) and (-2, 0)
y-intercept: set x=0
0%5E2%2F4+%2B+y%5E2%2F16=1
y%5E2%2F16+=1
y%5E2+=10
y+=4 or y+=-4
x-intercepts are at (0, 4) and (0, -4)