# Quadratic locus equation with dynamic coordinates

- Author:
- Zoltán Kovács

- Topic:
- Coordinates

A quadratic locus equation in GeoGebra by using the synthetic definition. Dynamic coordinates.

- In Step 1 we create three free points A', B' and C'. They should be hidden in the final version of the applet, but for the explanation we just used gray color here.
- In Step 2 commands like
**A=DynamicCoordinates[A',round(x(A')),round(y(A'))]**were used to set up constraints for points A, B and C. - In Step 3-4 we define line a and put point D on line a. Then in Steps 5-6 point E is constructed by Euclidean steps (as previously).
- Now the locus of point E while point D is moving on line a, is to be defined (Step 7, as previously).
- Finally in Step 8 we obtain the equation of the locus.
- Now we can also hide points A', B' and C' by right-clicking on them and disable the Show Object option.