<< Chapter < Page Chapter >> Page >

Identify the conic for each of the following without rotating axes.

  1. x 2 9 x y + 3 y 2 12 = 0
  2. 10 x 2 9 x y + 4 y 2 4 = 0
  1. hyperbola
  2. ellipse
Got questions? Get instant answers now!

Access this online resource for additional instruction and practice with conic sections and rotation of axes.

Key equations

General Form equation of a conic section A x 2 + B x y + C y 2 + D x + E y + F = 0
Rotation of a conic section x = x cos   θ y sin   θ y = x sin   θ + y cos   θ
Angle of rotation θ , where  cot ( 2 θ ) = A C B

Key concepts

  • Four basic shapes can result from the intersection of a plane with a pair of right circular cones connected tail to tail. They include an ellipse, a circle, a hyperbola, and a parabola.
  • A nondegenerate conic section has the general form A x 2 + B x y + C y 2 + D x + E y + F = 0 where A , B and C are not all zero. The values of A , B , and C determine the type of conic. See [link] .
  • Equations of conic sections with an x y term have been rotated about the origin. See [link] .
  • The general form can be transformed into an equation in the x and y coordinate system without the x y term. See [link] and [link] .
  • An expression is described as invariant if it remains unchanged after rotating. Because the discriminant is invariant, observing it enables us to identify the conic section. See [link] .

Section exercises

Verbal

What effect does the x y term have on the graph of a conic section?

The x y term causes a rotation of the graph to occur.

Got questions? Get instant answers now!

If the equation of a conic section is written in the form A x 2 + B y 2 + C x + D y + E = 0 and A B = 0 , what can we conclude?

Got questions? Get instant answers now!

If the equation of a conic section is written in the form A x 2 + B x y + C y 2 + D x + E y + F = 0 , and B 2 4 A C > 0 , what can we conclude?

The conic section is a hyperbola.

Got questions? Get instant answers now!

Given the equation a x 2 + 4 x + 3 y 2 12 = 0 , what can we conclude if a > 0 ?

Got questions? Get instant answers now!

For the equation A x 2 + B x y + C y 2 + D x + E y + F = 0 , the value of θ that satisfies cot ( 2 θ ) = A C B gives us what information?

It gives the angle of rotation of the axes in order to eliminate the x y term.

Got questions? Get instant answers now!

Algebraic

For the following exercises, determine which conic section is represented based on the given equation.

9 x 2 + 4 y 2 + 72 x + 36 y 500 = 0

Got questions? Get instant answers now!

x 2 10 x + 4 y 10 = 0

A B = 0 , parabola

Got questions? Get instant answers now!

2 x 2 2 y 2 + 4 x 6 y 2 = 0

Got questions? Get instant answers now!

4 x 2 y 2 + 8 x 1 = 0

A B = 4 < 0 , hyperbola

Got questions? Get instant answers now!

4 y 2 5 x + 9 y + 1 = 0

Got questions? Get instant answers now!

2 x 2 + 3 y 2 8 x 12 y + 2 = 0

A B = 6 > 0 , ellipse

Got questions? Get instant answers now!

4 x 2 + 9 x y + 4 y 2 36 y 125 = 0

Got questions? Get instant answers now!

3 x 2 + 6 x y + 3 y 2 36 y 125 = 0

B 2 4 A C = 0 , parabola

Got questions? Get instant answers now!

3 x 2 + 3 3 x y 4 y 2 + 9 = 0

Got questions? Get instant answers now!

2 x 2 + 4 3 x y + 6 y 2 6 x 3 = 0

B 2 4 A C = 0 , parabola

Got questions? Get instant answers now!

x 2 + 4 2 x y + 2 y 2 2 y + 1 = 0

Got questions? Get instant answers now!

8 x 2 + 4 2 x y + 4 y 2 10 x + 1 = 0

B 2 4 A C = 96 < 0 , ellipse

Got questions? Get instant answers now!

For the following exercises, find a new representation of the given equation after rotating through the given angle.

3 x 2 + x y + 3 y 2 5 = 0 , θ = 45°

Got questions? Get instant answers now!

4 x 2 x y + 4 y 2 2 = 0 , θ = 45°

7 x 2 + 9 y 2 4 = 0

Got questions? Get instant answers now!

2 x 2 + 8 x y 1 = 0 , θ = 30°

Got questions? Get instant answers now!

2 x 2 + 8 x y + 1 = 0 , θ = 45°

3 x 2 + 2 x y 5 y 2 + 1 = 0

Got questions? Get instant answers now!

4 x 2 + 2 x y + 4 y 2 + y + 2 = 0 , θ = 45°

Got questions? Get instant answers now!

For the following exercises, determine the angle θ that will eliminate the x y term and write the corresponding equation without the x y term.

x 2 + 3 3 x y + 4 y 2 + y 2 = 0

θ = 60 , 11 x 2 y 2 + 3 x + y 4 = 0

Got questions? Get instant answers now!

4 x 2 + 2 3 x y + 6 y 2 + y 2 = 0

Got questions? Get instant answers now!

9 x 2 3 3 x y + 6 y 2 + 4 y 3 = 0

θ = 150 , 21 x 2 + 9 y 2 + 4 x 4 3 y 6 = 0

Got questions? Get instant answers now!

−3 x 2 3 x y 2 y 2 x = 0

Got questions? Get instant answers now!

16 x 2 + 24 x y + 9 y 2 + 6 x 6 y + 2 = 0

θ 36.9 , 125 x 2 + 6 x 42 y + 10 = 0

Got questions? Get instant answers now!

x 2 + 4 x y + 4 y 2 + 3 x 2 = 0

Got questions? Get instant answers now!

x 2 + 4 x y + y 2 2 x + 1 = 0

θ = 45 , 3 x 2 y 2 2 x + 2 y + 1 = 0

Got questions? Get instant answers now!

4 x 2 2 3 x y + 6 y 2 1 = 0

Got questions? Get instant answers now!

Graphical

For the following exercises, rotate through the given angle based on the given equation. Give the new equation and graph the original and rotated equation.

y = x 2 , θ = 45

2 2 ( x + y ) = 1 2 ( x y ) 2

Got questions? Get instant answers now!

x 2 4 + y 2 1 = 1 , θ = 45

( x y ) 2 8 + ( x + y ) 2 2 = 1

Got questions? Get instant answers now!

y 2 16 + x 2 9 = 1 , θ = 45

Got questions? Get instant answers now!

y 2 x 2 = 1 , θ = 45

( x + y ) 2 2 ( x y ) 2 2 = 1

Got questions? Get instant answers now!

x = ( y 1 ) 2 , θ = 30

3 2 x 1 2 y = ( 1 2 x + 3 2 y 1 ) 2

Got questions? Get instant answers now!

x 2 9 + y 2 4 = 1 , θ = 30

Got questions? Get instant answers now!

For the following exercises, graph the equation relative to the x y system in which the equation has no x y term.

x 2 + 10 x y + y 2 6 = 0

Got questions? Get instant answers now!

x 2 10 x y + y 2 24 = 0

Got questions? Get instant answers now!

4 x 2 3 3 x y + y 2 22 = 0

Got questions? Get instant answers now!

6 x 2 + 2 3 x y + 4 y 2 21 = 0

Got questions? Get instant answers now!

11 x 2 + 10 3 x y + y 2 64 = 0

Got questions? Get instant answers now!

21 x 2 + 2 3 x y + 19 y 2 18 = 0

Got questions? Get instant answers now!

16 x 2 + 24 x y + 9 y 2 130 x + 90 y = 0

Got questions? Get instant answers now!

16 x 2 + 24 x y + 9 y 2 60 x + 80 y = 0

Got questions? Get instant answers now!

13 x 2 6 3 x y + 7 y 2 16 = 0

Got questions? Get instant answers now!

4 x 2 4 x y + y 2 8 5 x 16 5 y = 0

Got questions? Get instant answers now!

For the following exercises, determine the angle of rotation in order to eliminate the x y term. Then graph the new set of axes.

6 x 2 5 3 x y + y 2 + 10 x 12 y = 0

Got questions? Get instant answers now!

6 x 2 5 x y + 6 y 2 + 20 x y = 0

θ = 45

Got questions? Get instant answers now!

6 x 2 8 3 x y + 14 y 2 + 10 x 3 y = 0

Got questions? Get instant answers now!

4 x 2 + 6 3 x y + 10 y 2 + 20 x 40 y = 0

θ = 60

Got questions? Get instant answers now!

8 x 2 + 3 x y + 4 y 2 + 2 x 4 = 0

Got questions? Get instant answers now!

16 x 2 + 24 x y + 9 y 2 + 20 x 44 y = 0

θ 36.9

Got questions? Get instant answers now!

For the following exercises, determine the value of k based on the given equation.

Given 4 x 2 + k x y + 16 y 2 + 8 x + 24 y 48 = 0 , find k for the graph to be a parabola.

Got questions? Get instant answers now!

Given 2 x 2 + k x y + 12 y 2 + 10 x 16 y + 28 = 0 , find k for the graph to be an ellipse.

4 6 < k < 4 6

Got questions? Get instant answers now!

Given 3 x 2 + k x y + 4 y 2 6 x + 20 y + 128 = 0 , find k for the graph to be a hyperbola.

Got questions? Get instant answers now!

Given k x 2 + 8 x y + 8 y 2 12 x + 16 y + 18 = 0 , find k for the graph to be a parabola.

k = 2

Got questions? Get instant answers now!

Given 6 x 2 + 12 x y + k y 2 + 16 x + 10 y + 4 = 0 , find k for the graph to be an ellipse.

Got questions? Get instant answers now!

Questions & Answers

what's atoms
Achol Reply
discuss how the following factors such as predation risk, competition and habitat structure influence animal's foraging behavior in essay form
Burnet Reply
location of cervical vertebra
KENNEDY Reply
What are acid
Sheriff Reply
define biology infour way
Happiness Reply
What are types of cell
Nansoh Reply
how can I get this book
Gatyin Reply
what is lump
Chineye Reply
what is cell
Maluak Reply
what is biology
Maluak
what's cornea?
Majak Reply
what are cell
Achol
Explain the following terms . (1) Abiotic factors in an ecosystem
Nomai Reply
Abiotic factors are non living components of ecosystem.These include physical and chemical elements like temperature,light,water,soil,air quality and oxygen etc
Qasim
Define the term Abiotic
Marial
what is biology
daniel Reply
what is diffusion
Emmanuel Reply
passive process of transport of low-molecular weight material according to its concentration gradient
AI-Robot
what is production?
Catherine
hello
Marial
Pathogens and diseases
how did the oxygen help a human being
Achol Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply
Practice Key Terms 3

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Algebra and trigonometry. OpenStax CNX. Nov 14, 2016 Download for free at https://legacy.cnx.org/content/col11758/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Algebra and trigonometry' conversation and receive update notifications?

Ask