Add a Perpendicular - Cinderella Documentation
Description: The user's guide to the Interactive Geometry Software Cinderella

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# Add a Perpendicular

This mode allows a perpendicular to a line and through a point to be constructed with a press–drag–release sequence. The use of the mode is exactly analogous to add a parallel mode. The point through which the perpendicular should pass can also be generated in this mode. Constructing the perpendicular is a three-step procedure.

- Move the mouse over the line for which you want a perpendicular. Press the left mouse button. The perpendicular and the point through which it should pass are created.
- Hold the left button and drag the mouse. You can move the perpendicular and the new point to the desired position.
- Release the mouse. The construction is frozen. The definition of the new point is adapted according to the position at which you release the mouse:
- If the mouse pointer is over an existing point, then this point is taken.
- If the mouse pointer is over the intersection of two elements (line, circle, or conic), then this intersection is automatically constructed and taken as the new point.
- If the mouse pointer is over just one element (line or circle), then a point is constructed that is constrained to this element. This point is taken as the new point.
- Otherwise, a free point is added.

#### Synopsis

Add a perpendicular mode creates a perpendicular with a press–drag–release sequence.

#### Caution

The definition of perpendicularity depends on the chosen geometry.

#### See Also

- Add a Line
- Add a Parallel