# Locus Tool

From GeoGebra Manual

Revision as of 08:54, 28 July 2015 by Sabrina.azesberger (talk | contribs)

- Select a point
*B*that depends on another point*A*and whose locus should be drawn. Then, click on point*A*to create the locus of point*B*(see also Locus command). **Note:**Point*A*has to be a point on an object (e. g. line, segment/interval, circle).**Example:**

- Type
`f(x) = x^2 – 2 x – 1`

into the*Input Bar*and press the*Enter-key*. - Place a new point
*A*on the*x*-axis (see Point tool; see Point command). - Create point
`B = (x(A), f'(x(A)))`

that depends on point*A*. - Select tool and successively click on point
*B*and point*A*. - Drag point
*A*along the*x*-axis to see point*B*moving along its locus line.

- Type

Warning: | Locus is undefined, if the dependent point depends on Point Command with two parameters or PathParameter Command. |