Construction Circle Concentric with Other Circle

Concentric circles creation mode can be activated using the following automenu option of the Circle command:

The mode may also be called directly from the ribbon:

Upon activating the mode, perform following actions for creating a circle:

1. Select a circle, which the new circle should be tangent to:

If the concentric circles creation mode is activated using keyboard from the Circle command, then the construction circle nearest to cursor gets selected instantly at the moment of pressing the mode's hotkey.
If the mode is activated using mouse (no matter if it's done directly from the ribbon or from the Circle command), then you have to additionally press within drawing window for selecting the nearest construction circle. When using this method of activating the mode, instead of selecting a construction circle, you may select a graphic line (circle or circular arc) by moving the cursor over it and pressing <Enter>. In such case, a construction circle coinciding with the selected graphic line will be created automatically, and such construction circle will be selected for creating a concentric circle.

2. Specify the displacement (difference between radius of the new circle and radius of the selected circle) in one of the following ways:

•Type a displacement value or a name of a variable via keyboard into the input box of the parameters window. Then press <Enter> or click anywhere within drawing window for finishing the input.

•Place the cursor at an arbitrary point of drawing window and then press or <Enter>. The displacement value will be calculated so, that it ensures passing of the new circle through such point.

Regardless of the way of definition, displacement value is saved in ellipse parameters and can be edited later. Positive displacement means, that radius of the new circle is bigger than the radius of the initial one, negative displacement means the opposite. If the cursor is inside initial circle, when defining the displacement, then the minus sign is automatically added in front of the displacement input box. In such case, in order to type in a positive value, you have to either move the cursor out of the initial circle, or type in a minus before the value (minus times minus equals plus).

Example of creating a construction circle with positive displacement

       

Example of creating a construction circle with negative displacement

 

After creating a circle the command returns to the initial state.