As you edit your drawing, you may need to separately adjust some dimensions. You can trim and extend all forms of linear and ordinate dimensions. To trim or extend a linear dimension, AutoCAD LT draws an imaginary line (nonprinting) between the two extension line definition points.
AutoCAD LT trims or extends the imaginary line and then adjusts the dimension accordingly. To trim or extend an ordinate dimension, AutoCAD LT moves the feature location point (2) to the boundary edge perpendicular to the measured ordinate (1), so the ordinate value remains unchanged.
If the edited object is not parallel to the dimension definition points, as shown in the following illustration, the imaginary line technique used by AutoCAD LT probably will not produce the result you want. The following figure illustrates extending a linear dimension. The dimension extends to where the imaginary line meets the selected feature (1).
In these situations, stretch the dimension rather than trimming or extending it. You cannot trim a dimension and split it in two by cutting a portion out of the middle unless you explode it.