Extension lines are normally created at a perpendicular angle to the dimension line. You can change the angle of the extension lines, however, so that they tilt relative to the dimension line.
To make oblique extension lines
Choose Dimensions > Oblique.
Select the linear dimension, and then press Enter.
Type the obliquing angle, and then press Enter.
Command line DIMEDIT
Select the dimension to be made oblique (A), and then type the obliquing angle.
TIP To align the oblique angle if you don't know the exact measurement, use snaps to pick two points on the entity.
DDEDIT: Edits text, dimension text, attribute definitions, and feature control frames
DIMEDIT: Edits dimensions
DIMTEDIT: Moves and rotates dimension text
PROPERTIES: Controls properties of existing objects
System Variables Reference
DIMCLRT: Assigns colors to dimension text
DIMDSEP: Specifies a single-character decimal separator to use when creating dimensions whose unit format is decimal
DIMJUST: Controls the horizontal positioning of dimension text
DIMTAD: Controls the vertical position of text in relation to the dimension line
DIMTIH: Controls the position of dimension text inside the extension lines for all dimension types except ordinate
DIMTMOVE: Sets dimension text movement rules
DIMTOH: Controls the position of dimension text outside the extension lines
DIMTVP: Controls the vertical position of dimension text above or below the dimension line
DIMUPT: Controls options for user-positioned text
MTEXTED: Sets the primary and secondary text editors to use for multiline text objects