Envelope Command
From GeoGebra Manual
- Envelope( <Path>, <Point> )
- Creates the envelope equation of a set of output paths while the moving point is bound to another object.
An envelope is a curve that is tangent to each member of the family of the output paths at some point.
- Example: The contour of its trace will be the envelope of the ladder. Strictly speaking, GeoGebra computes the envelope of the entire line containing the ladder as a segment. Only such envelopes can be computed where the appropriate construction leads to an algebraic equation system.
Note: See also Locus, LocusEquation commands and GeoGebra Automated Reasoning Tools: A Tutorial.