Hey, I'm still kind of confused as to how to do this for this type of ellipse. If I see it done, than I'll probably be able to understand it better, thanks!
(Standard) Equation: [(x-9)^2/25] + [(y+2)^2/100] = 1
What's the center (9,-2), the foci, the major and minor axises, and the vertices of this ellipse?
Thanks again!
(Standard) Equation: [(x-9)^2/25] + [(y+2)^2/100] = 1
What's the center (9,-2), the foci, the major and minor axises, and the vertices of this ellipse?
Thanks again!
-
[(x - 9)² / 25] + [(y + 2)² / 100] = 1
Center (9, - 2)
Since the larger denominator is on the y side of the equation, the major axis will be parallel to the y axis ('a' is always the larger value), so
a² = 100
b² = 25
a = √(a²)
a = √100
a = ± 10
b = √(b²)
b = √25
b = ± 5
y-axis vertices will be 'a' units above and below the center, so
y = - 2 + 10
y = 8
and
y = - 2 - 10
y = - 12
y vertices (9, 8) & (9, - 12)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
x vertices will be 'b' units to the left and right of center, so
x = 9 + 5
x = 14
and
x = 9 - 5
x = 4
x vertices (14, - 2) & (4, - 2)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
The foci are 'c' units above and below center, and
______
c = √ a² - b²
_______
c = √100 - 25
___
c = √ 75
c = ± 8.66
Focus (9 , k ± 8.66), so
Focus (9, - 2 + 8.66)
Focus (9, 6.66)
and
Focus (9, - 2 - 8.66)
Focus (9, - 10.66)
Focii (9, 6.66) & (9, - 10.66)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Center (9, - 2)
Since the larger denominator is on the y side of the equation, the major axis will be parallel to the y axis ('a' is always the larger value), so
a² = 100
b² = 25
a = √(a²)
a = √100
a = ± 10
b = √(b²)
b = √25
b = ± 5
y-axis vertices will be 'a' units above and below the center, so
y = - 2 + 10
y = 8
and
y = - 2 - 10
y = - 12
y vertices (9, 8) & (9, - 12)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
x vertices will be 'b' units to the left and right of center, so
x = 9 + 5
x = 14
and
x = 9 - 5
x = 4
x vertices (14, - 2) & (4, - 2)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
The foci are 'c' units above and below center, and
______
c = √ a² - b²
_______
c = √100 - 25
___
c = √ 75
c = ± 8.66
Focus (9 , k ± 8.66), so
Focus (9, - 2 + 8.66)
Focus (9, 6.66)
and
Focus (9, - 2 - 8.66)
Focus (9, - 10.66)
Focii (9, 6.66) & (9, - 10.66)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯