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Cast shadow on another solid

Find the shadow of solid A (sphere, centre (14, 7, 12.75)) on solid B (cube, centre (12, 7, 3.75)), with a focus at (9, 6, 18.75).

Step-by-step solution

1. Project A onto the plane of each face of B facing the light.
2. Clip each projection with the corresponding face.
3. The shadow outline is the edges that appear only once when joining all pieces.
4. Check that the shadow only appears on the lit faces of B.

Result: shadow clipped on B; area 19.79 u².

On another body the shadow is clipped face by face: projecting onto an infinite plane is not enough.

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