Perpendicular lines

Do this for each GC file named Example 1, Example 2, Example 3, and Example 4. Open the file, move one or both of the points that the BLACK graph passes through so that the angle between the graphs [a(m,n)] is 90° (that is, make the two graphs perpendicular).

After moving the black graph so that it is perpendicular to the red graph, record the functions' rates of change in the table below. Each of Example 1, etc. will provide data for one row in the table.

File	Rate of change of first function	Rate of change of second function
Example 1
Example 2
Example 3
Example 4

Now, make a conjecture about how two linear functions' rates of change are related when their graphs are perpendicular.

Conjecture: If a linear function has a rate of change of m, then any function perpendicular to it will have a rate of change of ___________________.

Test your conjecture

Open the file Test Conjecture. Move the red graph to any position. Type a value for n that your conjecture says should make the first function's graph perpendicular to the second function's graph. Repeat this several times. Refine your conjecture if necessary.

Once you have a verified conjecture

Will the relationship you've conjectured always be true? How do you know? Look at this sketch to see what is going on.