# Linear locus equation

- Author:
- Zoltán Kovács

This applet demonstrates the basics of creating a locus equation object in GeoGebra.

- In Step 1 line AB (denoted by "a") is defined.
- In Step 2 its equation is also displayed (numerically).
- Now we define point C and mirror the line to the point (Step 3). How? In Step 4 we put point D on line a and mirror it on C (Step 5) to get point D'.
- Now the locus of point D' while point D is moving on line a, is the mirror image of line a, i.e. the mirrored line a' (Step 6).
- Finally in Step 7 we obtain the equation of line a'.

- Drag point D and check that D' is its mirror image to point C.
- Drag point C and try to search for such a place for it to make the coefficients of equation a' to be "larger" numbers. Note that these coefficients are always integers.
- Drag points A and B as well. Note that the equation of line a may contain numeric values, i.e. it is computed numerically.