C.a.R. > Documentation > Reference
Elementary Tools 



A free, movable point. Can be fixed immediately by holding down the shift key. 

A point on a circle or a line (or a segment, or a ray). 

A straight line through two points. 

A line segment between two points. 

A ray from one point through another point. 

A circle around a point through another point. 

The intersection between two lines, a line and a circle, or two circles. Either the two objects (generates both intersection points), or one of the intersection points (if there are two) can be selected. 
Shortcut Tools 


The parallel line to a line through a point. 

The line perpendicular to a line through a point. 

Circle around a point with a radius equal to the distance of two other points. The midpoint is chosen as last point. 

Middle point between two points. 
Fixed Objects 


Line segment between two points with fixed length. One of the end points must be movable. The length is determined by an arithmetic expression. 

Circle around a point with fixed radius (an expression). 

Angle of fixed size, given by two points and a size (an expression). The second point is the corner point of the angle. 
Movements 


Moves a point. 

The track of a point, or the curve belonging to a moving line (all generated lines are then tangents to the curve), when another point is moved. First selection determines the type of the track (point or line). The moving point is dragged with the left mouse button. 

Automatic track of a point, or curve belonging to moving line, when another point is moved on an object (line or circle). First selection (point or line) determines the type of the track. The line or circle must not depend on the moving point. The animation can be stopped by a mouse click. 

Animation of a construction by moving one point on a sequence of objects (circles or segments). The last object must be chosen twice to end the selection. The animation is stopped by a mouse click. 
Decorative Objects 


Angle through three points. The middle point is the corner of the angle. If the angle is allowed to become obtuse, its first and last point must be selected in mathematically positive order. 

Arithmetic expression. (Reference for expressions.) 

Filled polygon. The last point must be selected twice to stop the selection. 

Multiline text. The text is edited using a small internal editor. 

Conic section determined by 5 points. 
Other Tools 


Hiding and Unhiding objects. Hidden objects can be made visible using the tool. 

Run a macro. Shift click selects the previously run macro. (More about macros.) 
Generates a function or a curve. With Ctrl it generates a user defined function of several variables.  
Delete and Restore 



Deletes the last construction step, plus all invisible objects before that step. 

Deletes an arbitrary object and all its children (Be careful!). 

Restores the previously delete objects. This is only possible, while the construction has not been extended. 
Default Values for Objects 


Color. 

Type (for points). 

Thickness. 

Partial circles. 

Partial lines. 

Line segments should be vectors. 

Objects should display names. 

Objects have long names ("Point 1" instead of "P1). 

Objects display their value. 

Angles may become obtuse. 

Filled objects nontransparent by default. 
Display Options 


Show all hidden objects. 

Show only objects of a selected color (black plus another color). 
Other Tools 


Records a macro. The tool becomes (select parameters), and finally (enter targets). 

Display a grid. When the grid is visible, objects snap. 

Enter a comment for this construction. With shift: Enter a text for this assignment. 

The construction is done visually, not in the descriptive mode. 
Zoom with the mouse.  

Replay of the construction. Only visible steps are displayed. 
Context sensitive help. 
C.a.R. > Documentation > Reference