# Cross Product Applet Worksheet

This worksheet is designed to build familiarity with the cross product of two vectors in three space.  This can be done with the applets obtained by following either of the following links:
http://www.slu.edu/classes/maymk/banchoff/CrossProductSliders.html
http://www.slu.edu/classes/maymk/banchoff/CrossProductTextBox.html
(The difference between the two applets is in the method of controlling the coordinates of the two vectors of which we are taking cross products.  One applet uses sliders while the other uses text boxes.  It is easier to get an exact value with text boxes.  It is easier to see movement and patterns with sliders.  Tastes will vary on which is easier.)

Spread windows where you can see them all.  Increase the size of the control panel so that you can see all the readout boxes.

1) Find the cross product of (1,1, 0) and (-1,1,1).  Find the cross product of (1,-1,0) and (-1,1,1).
What happens if you reverse the order of the two vectors?  What happens if you double the size of the two vectors?

2) Set the first vector to (1,-1,0) and rotate the graph so that you are looking at that vector head on.  What has happened to the rectangle bounded by the two vectors?  What is the visual relationship between the first vector and the cross product vector?
Move the second vector around and describe what happens to the cross product vector.

3) Set the first vector to (1,1,1) and the second vector to (1,k,-1) for some value of k.  Move k through a variety of values.  Which value of k makes the cross product smallest?  What can be said about the angle where the cross product is smallest?

Return to the SLU Calculus Applet page.

Last updated By Mike May, S.J., September 18, 2006.