Ask Experts Questions for FREE Help!
 

Free Answers in 3 Easy Steps

Register Now
3 Steps
 


Ask QuestionsprogressAnswer QuestionsprogressBuild ReputationprogressBecome an Expert
 
At Ask Me Help Desk you can ask questions in any topic and have them answered for free by our experts. To ask questions or participate in answering them you must register for a free account. By registering you will be able to:
  • Get free answers from experts in any of our 300+ topics.
  • Accept money for answers that you provide.
  • Communicate privately with other members (PM).
  • See fewer ads.
  Answer this Question    Ask about Math & Sciences    Ask about another Subject  
 

jordo6889
Oct 26, 2009, 01:55 PM
Find the equation in standard form of an ellipse with center at (0,0) minor axis of length 12, and foci at (0,-8) and (0,8).

Nhatkiem
Oct 26, 2009, 07:25 PM
Find the equation in standard form of an ellipse with center at (0,0) minor axis of length 12, and foci at (0,-8) and (0,8).

the general standard form of an ellipse is

(\frac{x}{a})^2+(\frac{y}{b})^2=1

where a and b are the radii of your major and minor axis.:)

ebaines
Oct 27, 2009, 07:20 AM
Nhatkiem's suggestion will let you determine the value of b, but to find a you need to use the fact that :


a^2 - b^c = F^2


where F is the distance from the center of the ellipse to the focal point(s).

Also, don't forget that a and b are the lengths of the semi-major and semi-minor axes, respectively.

Nhatkiem
Oct 27, 2009, 09:13 AM
Nhatkiem's suggestion will let you determine the value of b, but to find a you need to use the fact that :


a^2 - b^c = F^2


where F is the distance from the center of the ellipse to the focal point(s).

Also, don't forget that a and b are the lengths of the semi-major and semi-minor axes, respectively.

hmm I always thought the definition for minor/major axis were dependent one which ones were longer, meaning the definition of a and b were interchangeable depending on lengths:confused: Been a while since ive done this ellipse .. boo.

ebaines
Oct 27, 2009, 09:25 AM
hmm I always thought the definition for minor/major axis were dependent one which ones were longer, meaning the definition of a and b were interchangeable depending on lengths:confused: Been a while since ive done this ellipse .. boo.

Yes - you are right - the a dimension is along the x axis, and the b along the y axis. If a > b then a is the semi-major axis length and b is the semi-minor length. I jumped ahead a bit and said that a is the semi-major and b the semi-minor, essentially giving away that the ellipse is stretched horizontaly (not vertically). The point I was trying to make was to distinguish between the minor axis length and the semi-minor laxis ength.