How to use geometric sketchpad to draw trajectory animation with moving points? In the geometric sketchpad, moving points to draw trajectory animation is usually achieved by dragging points, but this method is less efficient. This article will introduce a more efficient way to animate moving point trajectories, using variables and commands, which allows us to easily create repetitive and precise trajectory animations.
The second definition of ellipse: Assume that the ratio of the distance between the moving point M (x, y) and the fixed point F (c, 0) and the distance from it to the fixed straight line l: x=a2/c is a constant ( a>c>0), then the trajectory of point M is an ellipse. Point F is a focus of the ellipse, and the straight line l is the directrix in the ellipse corresponding to the focus F. Constant e=c/a(0). The specific operations are as follows:
To create an animation with a fixed endpoint and a trajectory animation of the midpoint of the line segment with the other endpoint moving on a fixed circle, the operation process is as follows:
Select a circle tool , draw a circle arbitrarily on the drawing board with the center point O; select the [Line Segment Tool] and draw the line segment DC, D is the vertex and C is the moving point; select the [Circle Tool] on the left sidebar and draw a circle arbitrarily on the drawing board with the center point is O; select [Line Segment Tool] and draw a line segment DC, D is the vertex, and C is the moving point.
Step 2 Select circle O and point C, click [Edit] on the upper menu bar - [Merge points to circle], this will ensure that when point C moves, it will always be in the circle superior.
Construct the midpoint of the line segment. Select the segment CD, click [Construction] - [Midpoint] in the upper menu bar to get the midpoint of the line segment, and use the label tool to label the midpoint P.
Create action buttons. Select point C. Note that the circle cannot be selected. Click [Edit] on the upper menu bar - operation button - animation. In the pop-up dialog box, the movement speed and direction are default, and click [OK]. At this time, there is an additional button in the workspace. At this time, if you click the button, point C will move on the circle, but point P has not left a trace.
Tracking the midpoint. Use the [Move Tool] to select point P, click [Display] - [Tracking Midpoint] in the upper menu bar,
Click the [Animation Point] button, obviously, you can see The trajectory out of point P is a circle. During exercise, you can stop anywhere by pressing the button, and start moving again by pressing it again. This animation is perfect.
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