##
What's the Point?

The applet on this page let's you draw and find points in the
Cartesian Coordinate system.

Clicking on the Applet brings up a Control Window and a Drawing
Window. To exit the program click again on the applet, or click on
"Quit" in the Control Window. When using the applet for the first
time click on "New" a few times to see a point in the Drawing Window
and its coordinates in the Control Window. You can resize the Drawing
Window if you wish.

Points lie at the intersections of the green grid lines in the Drawing
Window and can be specified with one digit beyond the decimal point.
Clicking elsewhere, or entering more digits, causes the point or its
coordinates to be rounded.

You can use the software in five modes, selected by the menu shown in
blue in control window::

**Show Point.** You enter numbers in the text fields of the
control window and the corresponding point appears in the drawing
window.

**Show Coordinates.** You click on a point in the drawing widow and
its coordinates show up in the text fields of the Control Window.

**Guess Point.** You locate the point in the Drawing Window
whose coordinates are given in the Control Window, and click on that
point. If you guessed right the point will be drawn, if you are
wrong nothing happens.

**Guess Coordinates.** You figure out the coordinates of the
point drawn in the Drawing Window and enter them in the Control
Window. If you are correct then the appropriate text field changes
color, and your coordinate is displayed by it.

**Examples.** The software shows both the point and its
coordinates. This is the default mode. See another point by clicking on "New" in the control window.

The Controls in the Control Window have the following effects:

**Quit** exits the software.

**New** computes a new random point.

**Show** answers the question for you if you wish.

- The blue
**menu** selects the appropriate mode as described above.
The default is **Examples** and the initial point is the origin.

**Quadrant** toggles the specification of the quadrants on and
off. The default is off.

- A green background in the text fields indicates that the
number in the field corresponds with point, a purple background
indicates the number is missing or incorrect (or you have not yet
pressed "Enter".) In some modes the system will not let you enter a
number and replace your input with the actual coordinate or a blank space.