Focus and Directrix of Ellipse. Focus and Directrix of Ellipse In the presence of a point F and a straight line d, ellipse can be characterized is the locus of points P whose distances to F and d are in a fixed ratio less than 1: The point is called a focus and the line a directrix of the ellipse. This property is often taken for a definition of ellipse. For every ellipse there are two focus/directrix combinations. The line joining the foci is the axis of summetry of the ellipse and is perpendicular to both directrices. Below is an interactive illustration. Drag the point on the ellipse to see how the distances to a focus or directrix change. Conic Sections > Ellipse |Activities||Contact||Front page||Contents||Geometry||Store| Copyright © 1996-2015 Alexander Bogomolny CITE THIS PAGE AS:A. Please enable JavaScript to view the <a href=" <A HREF=" AddThis Sharing Share BufferTumblrHootsuiteFacebookMore Hide Show AddThisPrivacy. Exploring Multivariable Calculus.
And then relaunch Chrome. Instructors: If you are an instructor using this project in any way, please send me an email to let me know of your interest. I would love to see more people using the materials from this project, and it is important that I be able to report how the project is doing to the NSF. I also encourage anyone who is interested in this project to take the time to write something on the discussion board. You will need to become a member to do this, but I am the only one who will see this member information. It is a private website, and membership makes it easier to keep spam from being placed on the discussion board. The following PDF documents give more information about the goals and current state of the project. 9-27-2011 Graph implicit equations in spherical or cylindrical coordinates like rho^2 = -sec(2ϕ) or r^2*theta^2 = r +theta.Implicit surfaces/equations can now be graphed in spherical and cylindrical coordinates as well as in cartesian coordinates.
June 29, 2011. Www.mathinscience.info/public/conic_sections/folding_conic_sections.pdf. Some fun teaching Vectors | Think for Yourself.
Circle/Angle Stuff. A Billion Nickels – 3 Acts « Zero-Knowledge Proofs. November 5, 2011 by John Scammell I support mostly high school math teachers. I work with colleagues who support K-9 teachers. Last week, I eavesdropped on two of them as they tried to come up with a 3 Act Math Story in style of Dan Meyer that would apply to division 1 students. This week’s Parks and Recreation may have provided us with one. You be the judge. Act One Click on Andy to play the movie. Act Two Find out what the students wonder about and what information they will need to answer their questions. Act Three The good folks over at Parks and Recreation didn’t film the right answer for us. . $1000 = 20 000 Nickels Sequels Could Andy hold 20 000 nickels?
Edit (June 16, 2013) The story about Samsung paying off an Apple lawsuit using truckloads of nickels is a really nice sequel to this one. Like this: Like Loading... Falling Rocks. Falling Glowsticks.
Dueling Discounts. By Dan Meyer prologue 7.RP.3 MP.4 download act one 1. Which coupon should I use? Image — the coupons act two 3. Sequel 5. Lesson content CC BY-NC 3.0 Dan Meyer. The Taco Cart. By Dan Meyer prologue 8.G.7 F-IF.4 MP.4 download act one 1. Who will reach the taco cart first? 2. Write a guess. Act two 3. Act three video — the answer sequel 4. Lesson content CC BY-NC 3.0 Dan Meyer Map content by Google Maps. Coke v. Sprite. Prologue act one 1. Which glass now contains more of its original soda? 2. Write down your guess. Video — coke & sprite act two 3. Act three sequel 4. What Light Looks Like.
Prologue act one 1. Is reality closer to the top video or the bottom? 2. Using your finger, show just how long it takes light to get from the Earth to the Moon. Video — flashlight on act two 3. Act three video — answer sequel 4.