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Solution - Properties of ellipses

Equation in standard form x294+y2949=1
\frac{x^2}{\frac{9}{4}}+\frac{y^2}{\frac{9}{49}}=1
Center (0,0)
(0, 0)
Radius of the major axis 1.5
1.5
Vertex_1 (1.5,0)
(1.5, 0)
Vertex_2 (1.5,0)
(-1.5, 0)
Radius of the minor axis 0.429
0.429
Co-vertex_1 (0,0.429)
(0, 0.429)
Co-vertex_2 (0,0.429)
(0, -0.429)
Focal length 1.437
1.437
Focus_1 (1.437,0)
(1.437, 0)
Focus_2 (1.437,0)
(-1.437, 0)
Area 0.644π
0.644π
x-intercepts (32,0),(-32,0)
(\frac{3}{2}, 0), (-\frac{3}{2}, 0)
y-intercepts (0,37),(0,-37)
(0, \frac{3}{7}), (0, -\frac{3}{7})
Eccentricity 0.958
0.958

Other Ways to Solve

Properties of ellipses

Step-by-step explanation

1. Find the standard form

To find the standard form of an ellipse, make the right side of the equation equal to 1:

4x2+49y2=9

Divide both sides by 9

4x29+49y29=99

Simplify the expression

49x2+499y2=1

x294+y2949=1

Because the denominator of x (94) is bigger than the denominator of y (949), it represents the major axis (94=a2), making this a horizontal ellipse equation:
(x-h)2a2+(y-k)2b2=1

2. Find the center

h represents the x-offset from the origin.
k represents the y-offset from the origin.
To find the values of h and k, use the horizontal ellipse standard form:
(x-h)2a2+(y-k)2b2=1

x294+y2949=1
h=0
k=0
Center: (0,0)

3. Find the radius of the major axis

a represents the longer radius of the ellipse, which is equal to half of the major axis. This is called the semi-major axis.
To find the value of a, use the horizontal ellipse standard form:
(x-h)2a2+(y-k)2b2=1

x294+y2949=1
a2=94
Take the square root of both sides of the equation:
a=1.5

Because a represents a distance, it only has a positive value.

4. Find the vertices

In a horizontal ellipse, the major axis runs parallel to the x-axis and passes through the ellipse's vertices. Find the vertices by adding and subtracting a from the x-coordinate (h) of the center.

To find vertex_1, add a to the x-coordinate (h) of the center:
Vertex_1: (h+a,k)
Center: (h,k)=(0,0)
h=0
k=0
a=1.5
Vertex_1: (0+1.5,0)
Vertex_1: (1.5,0)

To find vertex_2, subtract a from the x-coordinate (h) of the center:
Vertex_2: (ha,k)
Center: (h,k)=(0,0)
h=0
k=0
a=1.5
Vertex_2: (01.5,0)
Vertex_2: (1.5,0)

5. Find the radius of the minor axis

b represents the shorter radius of the ellipse, which is equal to half of the minor axis. This is called the semi-minor axis.
To find the value of b, use the horizontal ellipse standard form:
(x-h)2a2+(y-k)2b2=1

x294+y2949=1
b2=949
Take the square root of both sides of the equation:
b=0.429
Because b represents a distance, it only has a positive value.

6. Find the co-vertices

In a horizontal ellipse, the minor axis runs parallel to the y-axis and passes through the ellipse's co-vertices.
Find the co-vertices by adding and subtracting b from the y-coordinate (k) of the center.

To find co-vertex_1, add b to the y coordinate (k) of the center:
Co-vertex_1: (h,k+b)
Center: (h,k)=(0,0)
h=0
k=0
b=0.429
Co-vertex_1: (0,0+0.429)
Co-vertex_1: (0,0.429)

To find co-vertex_2, subtract b from the y-coordinate (k) of the center:
Co-vertex_2: (h,kb)
Center: (h,k)=(0,0)
h=0
k=0
b=0.429
Co-vertex_2: (0,00.429)
Co-vertex_2: (0,0.429)

7. Find the focal length

Focal length is the distance from the ellipse's center to each focal point and is usually represented by f.

To find f, use the formula:
f=a2-b2
a2=94
b2=949
Plug a2 and b2 into the formula and simplify:

f=94-949

f=405196

f=1.437

Because f represents a distance, it only has a positive value.

8. Find the foci

In a horizontal ellipse, the major axis runs parallel to the x-axis and through the foci.
Find the foci by adding and subtracting f from the x-coordinate (h) of the center.

To find focus_1, add f to the x-coordinate (h) of the center:
Focus_1: (h+f,k)
Center: (h,k)=(0,0)
h=0
k=0
f=1.437
Focus_1: (0+1.437,0)
Focus_1: (1.437,0)

To find focus_2, subtract f from the x-coordinate (h) of the center:
Focus_2: (hf,k)
Center: (h,k)=(0,0)
h=0
k=0
f=1.437
Focus_2: (01.437,0)
Focus_2: (1.437,0)

9. Find the area

Use the formula for the area of an ellipse to find the ellipse's area:
π·a·b
a=1.5
b=0.429
Plug a and b into the formula and simplify:

π·1.5·0.429

π·0.644

The area equals 0.644π

10. Find the x and y-intercepts

To find the x-intercept(s), plug 0 in for y in the ellipse's standard equation and solve the resulting quadratic equation for x.
Click here for a step-by-step explanation of the quadratic equation.

x294+y2949=1

x294+02949=1

x1=32

x2=-32

To find the y-intercept(s), plug 0 in for x in the ellipse's standard equation and solve the resulting quadratic equation for y.
Click here for a step-by-step explanation of the quadratic equation.

x294+y2949=1

0294+y2949=1

y1=37

y2=-37

11. Find the eccentricity

To find the eccentricity use the formula:
a2-b2a
a2=94
b2=949
a=1.5
Plug a2 , b2 and ainto the formula:

94-9491.5

4051961.5

1.4371.5

0.958

The eccentricity equals 0.958

12. Graph

Why learn this

If you cut a carrot in half across its grain (like this: =|> ) the resulting cross-section would be circular and, therefore, somewhat easy to measure. But what if you cut the same carrot across the grain at an angle (like this: =/> )? The resulting shape would be more of an ellipse and measuring it would prove to be a bit more difficult than measuring a plain old circle. But why would you need to measure the cross section of a carrot to begin with?
Well... you probably would not, but such occurrences of ellipses in nature are actually quite common, and understanding them from a mathematical perspective can be useful in many different contexts. Fields such as art, design, architecture, engineering, and astronomy all rely at times on ellipses - from painting portraits, to building homes, to measuring the orbit of moons, planets, and comets.

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