Trim
You can trim sketch entities, including
infinite lines, and extend
sketch entities (lines, centerlines, and arcs) to meet other entities.
Trim Entities 
includes options:
Power trim.
Trim multiple adjacent sketch entities by dragging the pointer across
the entities, or extend entities by selecting them and dragging the pointer.
Corner.
Trim or extend two sketch entities until they intersect at a virtual corner.
Trim away inside.
Trim open sketch entities inside two bounding entities.
Trim away outside.
Trim open sketch entities outside two bounding entities.
Trim to closest.
Trim or extend sketch entities to the closest intersection.