To trim an entity to an implied boundary

Do one of the following:

Choose Modify > Trim.
On the Modify toolbar, click the Trim tool ().
Type trim and then press Enter.

Select one or more cutting edges, and then press Enter.
In the prompt box, choose Edge Mode.
In the prompt box, choose Extend.
Select the entity to trim.
Select another entity to trim, or press Enter to complete the command.

Select the implied boundary edge (A), and then select the entities to trim (B).

Result.

How do I...

Trim several entities using the fence selection method