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2.2.5.1. GeoGebra link
Use the mouse to zoom in and out of the sphere to turn it.
Carefully take a look at the lines on the sphere's outer surface - meridians or circles in a vertical position and a parallel or circle in a horizontal position.
Move point A along the outer surface of the sphere with the mouse and pay attention to the change in the positions of the circles associated with it.
Turning the sphere, look at the orthogonal projections of the sphere and point A, and pay attention to the change in the visibility of the projections of point A in the top, front and left views projections.
2.2.5.2. GeoGebra link
To do the exercise, stop the animation - its button at the bottom left.
By moving the sliders, follow the change in orthogonal projections in the top and front view.
Please pay attention to the position and indication of the projections of points, both visible and invisible.
It is crucial to correctly understand the designation of the projection of a point - the correct reading of the drawing depends on it!
2.2.5.3. By moving the slider, look at getting the net of the regular polyhedron - dodecahedron placed in a sphere. You see that you can choose how to construct the net of a spherical surface. But in any case, replacing the sphere with a polyhedron is necessary. And the best net consists of a pretty large number of parts - see left.
2.2.5.4. Watch a video on how to draw a net of the spherical surface.
2.2.5.5. And to consolidate the information received, check how well you got knowledge about a sphere.
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