# parametric equations

• Jan 16th 2007, 04:11 PM
sarah s
parametric equations
I need help with parametric equations....i can't seem to figure out where to start when looking at a problem. The problems i will have to solve include looked at a diagram and figuring out the parametric equations for the trace of a movie point. Any suggestions?
• Jan 16th 2007, 04:15 PM
ThePerfectHacker
Quote:

Originally Posted by sarah s
I need help with parametric equations....i can't seem to figure out where to start when looking at a problem. The problems i will have to solve include looked at a diagram and figuring out the parametric equations for the trace of a movie point. Any suggestions?

Give a problem that you are unable to do.
• Jan 16th 2007, 06:18 PM
topsquark
Quote:

Originally Posted by sarah s
I need help with parametric equations....i can't seem to figure out where to start when looking at a problem. The problems i will have to solve include looked at a diagram and figuring out the parametric equations for the trace of a movie point. Any suggestions?

If I am understanding what you have to do correctly the I would suggest the following scheme:

Set the lower left corner of the screen as (0, 0). Then you can think of your trace as a series of coordinate points. Pick a starting point for your trace and call this t = 0. Call the coordinates of that point \$\displaystyle (x(0), y(0))\$.

Now pick a small distance along the path, small enough that the path is (roughly) a straight line over that distance. Record the coordinates of that point as \$\displaystyle (x(1), y(1))\$.

Using the same distance, find the coordinates of the next point, \$\displaystyle (x(2), y(2))\$. etc.

So you will have a list of coordinate points at "equal spacings" along the trace.

Now find a best fit function for the x - coordinates, and a separate best fit function for the y - coordinates. This will be your parametric representation of the trace.

-Dan