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Suppose a whispering chamber is 480 feet long and 320 feet wide.

  1. What is the standard form of the equation of the ellipse representing the room? Hint: assume a horizontal ellipse, and let the center of the room be the point ( 0 , 0 ) .
  2. If two people are standing at the foci of this room and can hear each other whisper, how far apart are the people? Round to the nearest foot.
  1. x 2 57 , 600 + y 2 25 , 600 = 1
  2. The people are standing 358 feet apart.
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Access these online resources for additional instruction and practice with ellipses.

Key equations

Horizontal ellipse, center at origin x 2 a 2 + y 2 b 2 = 1 ,   a > b
Vertical ellipse, center at origin x 2 b 2 + y 2 a 2 = 1 ,   a > b
Horizontal ellipse, center ( h , k ) ( x h ) 2 a 2 + ( y k ) 2 b 2 = 1 ,   a > b
Vertical ellipse, center ( h , k ) ( x h ) 2 b 2 + ( y k ) 2 a 2 = 1 ,   a > b

Key concepts

  • An ellipse is the set of all points ( x , y ) in a plane such that the sum of their distances from two fixed points is a constant. Each fixed point is called a focus (plural: foci).
  • When given the coordinates of the foci and vertices of an ellipse, we can write the equation of the ellipse in standard form. See [link] and [link] .
  • When given an equation for an ellipse centered at the origin in standard form, we can identify its vertices, co-vertices, foci, and the lengths and positions of the major and minor axes in order to graph the ellipse. See [link] and [link] .
  • When given the equation for an ellipse centered at some point other than the origin, we can identify its key features and graph the ellipse. See [link] and [link] .
  • Real-world situations can be modeled using the standard equations of ellipses and then evaluated to find key features, such as lengths of axes and distance between foci. See [link] .

Section exercises

Verbal

Define an ellipse in terms of its foci.

An ellipse is the set of all points in the plane the sum of whose distances from two fixed points, called the foci, is a constant.

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Where must the foci of an ellipse lie?

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What special case of the ellipse do we have when the major and minor axis are of the same length?

This special case would be a circle.

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For the special case mentioned above, what would be true about the foci of that ellipse?

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What can be said about the symmetry of the graph of an ellipse with center at the origin and foci along the y -axis?

It is symmetric about the x -axis, y -axis, and the origin.

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Algebraic

For the following exercises, determine whether the given equations represent ellipses. If yes, write in standard form.

4 x 2 + 9 y 2 = 36

yes; x 2 3 2 + y 2 2 2 = 1

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4 x 2 + 9 y 2 = 1

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

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4 x 2 8 x + 9 y 2 72 y + 112 = 0

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For the following exercises, write the equation of an ellipse in standard form, and identify the end points of the major and minor axes as well as the foci.

x 2 4 + y 2 49 = 1

x 2 2 2 + y 2 7 2 = 1 ; Endpoints of major axis ( 0 , 7 ) and ( 0 , 7 ) . Endpoints of minor axis ( 2 , 0 ) and ( 2 , 0 ) . Foci at ( 0 , 3 5 ) , ( 0 , 3 5 ) .

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x 2 + 9 y 2 = 1

x 2 ( 1 ) 2 + y 2 ( 1 3 ) 2 = 1 ; Endpoints of major axis ( 1 , 0 ) and ( 1 , 0 ) . Endpoints of minor axis ( 0 , 1 3 ) , ( 0 , 1 3 ) . Foci at ( 2 2 3 , 0 ) , ( 2 2 3 , 0 ) .

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Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Source:  OpenStax, Precalculus. OpenStax CNX. Jan 19, 2016 Download for free at https://legacy.cnx.org/content/col11667/1.6
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