Motion given by circular and point envelopes

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Specification of a motion

The following rules are valid for a motion given by circular envelope (a) of straight line a and point envelope (b) of straight line b:

- Straight line a is tangent line to the envelope (a) at each instant.

- Straight line b passes through point envelope (b) at each instant.

- Angle ψ formed by straight lines a and b does not change.

This motion and the motion given by two linear trajectories are inverse motions.

Animation of a motion (motion given by circular and point envelopes)

Fixed centrode (motion given by circular and point envelopes)

Trajectory of a point (motion given by circular and point envelopes)

Envelope of a circle (motion given by circular and point envelopes)

Envelope of a straigth line (motion given by circular and point envelopes)

Specification of inverse motion (motion given by circular and point envelopes)

- Straight line parallel to straight line a passing through the centre of circular envelope (a) becomes the trajectory of centre of moving circular envelope (a).

- Straight line b becomes the trajectory of moving point envelope (b).

- The distance between moving centre of circular envelope (a) and moving point envelope (b) does not change during the motion.

Moving centrode (motion given by circular and point envelopes)