
• When you draw a circle, you can select two points in the viewport or on a workplane to set the line which connects the two points as a mirror. For more information, see
Set a mirror for 2D geometrical elements.

To change from the radius mode to the diameter mode, • Click on the status bar or 
When you change from the radius mode to the diameter mode , the following circle commands change: • On the Modeling tab, in the Draw group, the Circle Center & Radius changes to Center & Diameter. • On the Modeling tab, in the Draw group, the Construction Circle Center & Radius changes to Center & Diameter. • On the Modeling tab, in the Modify 2D group, Radius changes to Diameter. 
In the diameter mode, the visual feedback shows the diameter of the circle as shown in the image below. To switch to diameter mode, see
Change 2D CoPilot settings. 
• To set the radius of a circle in the radius mode, press SPACEBAR, click on the Option Mini Toolbar (OMT), and type a value for the radius. You can also rightclick somewhere in the viewport, choose Set Radius from the context menu, and type a value for the radius. • To set the diameter of a circle in the diameter mode, press SPACEBAR, click on the Option Mini Toolbar (OMT), and type a value for the diameter. You can also rightclick somewhere in the viewport, choose Set Diameter from the context menu, and type a value for the diameter. 
You can use the Linear Bisector or the Angular Bisector command (onthefly) when you draw a circle; for example, to find the midpoint between two circles. • To use a linear bisector: ◦ Press X or, ◦ Rightclick and choose Linear Bisector on the context menu or, ◦ Press SPACEBAR or the assigned key and click on the Option Mini Toolbar (OMT). • To use an angular bisector: ◦ Press Y or, ◦ Rightclick and choose Angular Bisector on the context menu or, ◦ Press SPACEBAR or the assigned key and click on the OMT. 
You can use the Line Between 2 Points command (onthefly) to create a temporary line and then use the midpoint of this line as a reference to create circles. To create a temporary reference line between two points: a. Press M, or rightclick in the viewport and choose Line Between 2 Points on the context menu. Alternatively, press SPACEBAR or the assigned key and click on the OMT. b. Select any two points on the viewport. For example, you can select two opposite vertices of a rectangle. See
Example: Drawing a rectangle using a line between two points as a reference. 
To draw a circle relative to up to two elements, see
Draw an element relative to up to two elements. 
• Ensure that Automatic Tangent Circle by 3 Points is selected in
2D CoPilot Settings. By default, Automatic Tangent Circle by 3 Points is selected. • If you select the first element as tangent reference, the circle created has a tangent constraint and remains tangent to this element. 
• As you move the cursor over other 2D elements in the viewport, the 2D CoPilot automatically shows points on the elements where the circle is tangent to those elements. • In the diameter mode, the visual feedback shows the diameter of the circle. To switch to diameter mode, see
Change 2D CoPilot settings. 
When you mark the second and third points of the circle: • To set the radius of a circle in the radius mode, press SPACEBAR, click on the Option Mini Toolbar (OMT), and type a value for the radius. You can also rightclick somewhere in the viewport, choose Set Radius from the context menu, and type a value for the radius. • To set the diameter of a circle in the diameter mode, press SPACEBAR, click on the Option Mini Toolbar (OMT), and type a value for the diameter. You can also rightclick somewhere in the viewport, choose Set Diameter from the context menu, and type a value for the diameter. 
You can use the Linear Bisector or the Angular Bisector command (onthefly) when you draw a circle; for example, to find the midpoint between two circles. • To use a linear bisector: ◦ Press X or, ◦ Rightclick and choose Linear Bisector on the context menu or, ◦ Press SPACEBAR or the assigned key and click on the Option Mini Toolbar (OMT). • To use an angular bisector: ◦ Press Y or, ◦ Rightclick and choose Angular Bisector on the context menu or, ◦ Press SPACEBAR or the assigned key and click on the OMT. 
You can use the Line Between 2 Points command (onthefly) to create a temporary line and then use the midpoint of this line as a reference to create circles. To create a temporary reference line between two points: a. Press M, or rightclick in the viewport and choose Line Between 2 Points on the context menu. Alternatively, press SPACEBAR or the assigned key and click on the OMT. b. Select any two points on the viewport. For example, you can select two opposite vertices of a rectangle. See
Example: Drawing a rectangle using a line between two points as a reference. 
You can type a value for the radius before clicking the third point or element. 
When the 2D CoPilot is active, press SPACEBAR to open the Option Mini Toolbar (OMT) and select Geometry or Construction in the box to change the drawing mode. 