CONCEPT BY RICHARD TOOGOOD AND RON BLOND

HOW TO USE THIS APPLET

The slider area

The sliders change the parameters h, k and r in the quadratic relation ( x - h )² + ( y - k )² = r².

• Drag a slider to change the value of a parameter.
• The left and right arrow keys can be used to change the selected parameter [light blue].
• The up and down arrow keys can be used to increase or decrease the selected parameter. (Use this feature for fine adjustments.)
• If the arrow keys don't respond, click the cursor in the applet frame then try again.
• Drag a parameter scale to "move" it. (ie. Change the range but maintain the scale "length".)
• Drag towards or away from a parameter thumb to "re-scale" the scale.
• Select the corresponding parameter button to enter a value for a parameter.

The graph area

• Drag the center of the circle to move the circle in the coordinate system.
• Drag a location along the circle to change the radius of the circle.
• Click and drag any other location to see the coordinates of the cursor and locations along the circle.
• THE SHIFT KEY : Click and drag in the graph area to move the entire coordinate system.
• THE CONTROL KEY : Click and drag in the graph area towards or away from the origin to change the x and y axis scale.

Other

• Use the "RESET" button to restore the applet to the initial state.

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The following two applets are subsets of the applet at the top of this page. All three are for lessons on quadratic relations being written by Richard. The first applet below allows the user to vary h and k, where the radius of the circle is fixed at a value of one. The second applet below allows the user to vary r, where the center of the circle is fixed at at the origin.