Angle - Angle[]

In GeoGebra, angles can be entered in degrees (using the ° symbol) or radians (no unit/symbol). Recall: 1 ≈ 57° and 180° = π ≈ 3.14 .

Example: You can enter an angle α in degree (e. g., α = 60°) or in radians (e. g., α = pi/3).

Note: GeoGebra does all internal calculations in radians. The degree symbol (°) is nothing but the constant π/180 used to convert degree into radians.

Examples:

• If a = 30 is a number, then α = a° converts number a to an angle α = 30°, without changing its value.
• If you type in b = α / °, the angle α is converted back to the number b = 30, without changing its value.

Angle   
With this tool you can create angles in different ways (also see command Angle):

• Click on three points to create an angle between these points. The second point is the vertex of the angle.
• Click on two segments to create the angle between them.
• Click on two lines to create the angle between them.
• Click on two vectors to create the angle between them.
• Click on a polygon to create all angles of this polygon.      

Note: Angles are created in counter-clockwise orientation. Therefore, the order of selecting these objects is relevant for the Angle tool.

Note: If you want to limit the maximum size of an angle to 180°, un-check Allow Reflex Angle on tab Basic of the Properties Dialog.

Angle of given size   

Select two points A and B and type the angle’s size into the text field of the appearing window (also see command Angle). Note: This tool creates a point C and an angle α, where α is the angle ABC.

Note: Angles are created in counter clockwise orientation. Therefore, the order of selecting these objects is relevant for the Angle tool.

Note: If you want to limit the maximum size of an angle to 180°, un-check Allow Reflex Angle on tab Basic of the Properties Dialog.