Thursday, February 28, 2013

Some Geogebra Hints

Perhaps I should have made
 a real snowman instead
of playing with fake ones

Image by Benice
During our last snow day, I spent a large amount of time (for fear of embarrassment, I will not specify how long...) playing with geogebra. Along the way I learned a handful of tricks that I wanted to write down in one place. So, without further ado, here's an assorted (not random) list of tricks for working with geogebra:
  • Right-click and drag draws a box and zooms in on that box
  • Ctrl-Click and drag grabs the screen and moves it
  • Ctrl-Alt-Delete-Shift-Right-Click and drag infects your computer with millions of geogebra viruses. Don't try it -- the rest of my snow day was spent purging my hard drive and trying to save pictures of my daughters.
  • Entering a point with a semi-colon enters it in polar coordinates
      Ex: (4; 1) puts a point at a radius of 4 and angle of 1 radian (around 57degrees)
      Ex: (4; 30°) puts a point at a radius of 4 and an angle of 30° -- you can find the degree symbol off to the right if you click on the greek letter alpha and find degrees symbol
  • Actually, you can insert a degree symbol while typing by pressing Alt o
  • You can plot a complex number by using the imaginary number i, which you'll have to type using Alt i
  • To plot a function in polar form:
    1. Define your function in f(x) notation
    2. Create a slider to act as the Theta settings (from 0, to 2*pi, by pi/100 is good)
    3. Create a curve with the command:
          curve[f(t)*cos(t), f(t)*sin(t), t, 0, theta]
      To watch someone describe this process watch this video.
  • Actually, you can insert a theta symbol by pressing Alt-t 
  • and a pi symbol while typing by pressing Alt - you guessed it - p. If only microsoft word was that easy.
  • To put a picture into Geogebra is fairly easy, but to describe exactly where it goes, right click on it and go to position tab. Then you can type in the coordinates of the corners of the picture directly, or you can attach these coordinates to sliders so that you can control them dynamically. Often I like to put the picture as a background object, so that other things lie on top of it.

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