You can draw 2D circles and ellipses by using the Circle and Ellipse tools, respectively, in the Sketch menu.

Circle

Before you draw circles, choose whether you want to define circles with radii or both radii and diameters. You can do so from the Circular Annotations option in Settings.

If you're using an Apple Pencil, tap Circle and then tap the grid to place the center and drag your Apple Pencil until you reach the correct radius or diameter. If you want to redefine the shape’s radius or diameter, tap on the dimension label and add a value in the numpad. 

If you're using a mouse or trackpad, follow these steps: 

1. Select Circle in the Sketch tool menu. 
2. Click to add the center and circumference points. You can also type the radius or diameter to quickly define the length. 
3. Finish the sketch by pressing Return. 
   If you want to remove the shape, then press one of the following:
   • Delete (Backspace)
   • Escape
     Or, secondary click (right-click) with your mouse. 
4. Press the Escape key to drop the active sketching tool. 

When you select the drawn circle or its dimension label, you can see the radius or diameter, depending on your Circular Annotations setting.  

Ellipse

If you're using an Apple Pencil, tap Ellipse and place the center of your ellipse on the grid. Drag your Apple Pencil to create the shape. You can then define the major and minor axes by tapping on the dimension labels.

If you're using a mouse or trackpad, follow these steps:

1. Select Ellipse in the Sketch tool menu. 
2. Click to add the center and circumference points. 
3. Finish the sketch by pressing Return. 
   If you want to remove the shape, then press one of the following:
   • Delete (Backspace)
   • Escape
     Or, secondary click (right-click) with your mouse. 
4. Press the Escape key to drop the active sketching tool.