Fixed point line
A fixed point line is a straight line in geometry whose points are fixed points of a given image. For example, the mirror axis is a fixed point line for an axis reflection , since the reflection maps every point of the axis onto itself. A fixed point line is always a fixed line . The reverse of this statement is generally wrong. For example, the perpendiculars to the axis of an axis reflection are fixed lines, but not fixed point lines. With a shear there is a fixed point line and the straight lines parallel to it are fixed lines.
A fixed point line is a characteristic quantity of the figure. One speaks therefore of the fixed point line of an image . A perspective affinity always has a fixed point line.
literature
- Ernst-Georg Haffner: Linear Algebra for Dummies . Wiley, 2012, pp. 304-306
- Schülerduden - Mathematics I . Duden-Verlag, 8th edition, 2008, ISBN 978-3-411-04208-1 , p. 131
- Gert Bär: Geometry: An introduction to analytical and constructive geometry . Springer, 2013, pp. 78-79