Practice question · Multiple choice
A line is parallel to a plane when its direction dotted with the plane’s normal is zero. Why does perpendicularity to the NORMAL mean parallelism to the plane?
Hints
- Picture the normal sticking straight out of a tabletop.
- Which directions are perpendicular to it?
Show the answer
D. Because the normal points out, so perpendicular means within
Why
The normal encodes the whole plane in one vector. This is what makes plane geometry computable, every question about the surface becomes a dot product with its normal.
Practise Lines, Planes, and Geometric Transformations
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