Quadratic function is a mathematical model that describes the law of movement change in the objective world. When learning quadratic function, we have learned to draw quadratic function roughly by tracing points. In the geometric sketchpad, we can also draw a quadratic function accurately by tracing points. The method of drawing quadratic function by tracing points will be introduced in detail below.

Download address of Geometer's Sketchpad:

Win edition

/iclk/？ zoneid= 14448

Mac version

/iclk/？ zoneid= 14449

The specific operation steps are as follows:

The first step is to define three coordinate points.

Determine three coordinate points: (2,2), (-2,2), (1,-1).

Step two, draw some pictures.

(1) Open the geometry sketchpad software, and click Custom Tools-Function Tools-Three-Point Parabola 1 on the left toolbar. Then the plane rectangular coordinate system will automatically appear, as shown in the figure, so that we can easily find the coordinate points.

Automatic generation of plane rectangular coordinate system with custom tools

(2) Click Custom Tool-Function Tool-Parabola 2 on the left toolbar to cross three points, and find three points (2,2), (-2,2), (1,-1) in the coordinate system, and then automatically generate a quadratic function image, and the analytic function is displayed in the upper left corner.

Find three coordinate points in the coordinate system and automatically generate quadratic function images.

Step 3: Image adjustment

(1) scale adjustment

If you think there are more or less scales on the coordinate axis, we can find a unit point near the origin on the X axis, hold down the left mouse button and drag to adjust the density of the point.

Press and hold the unit point with the left mouse button, and drag left and right to adjust the density of the point.

(2) Position adjustment

If you are not satisfied with the position of the coordinate axis, you can press and hold the red dot above the origin to change the position.

Click the left mouse button to hold the origin and drag to change the position.

The method of drawing quadratic function image by tracing method in geometric sketchpad is introduced above. The operation is simple and you can practice more according to the tutorial. The vivid image of quadratic function can help us better understand quadratic function, and the courseware of geometric sketchpad about quadratic function can be used for reference.