Rotating Objects
To rotate an object using a reference angle
- From the Modify menu, choose Rotate.
- Select the object to rotate.
- Specify the base point for the rotation.
- Enter r (Reference).
- Do one of the following:
- Enter an absolute angle for the reference.
- Specify two point locations on the object being rotated for the reference.
- Then, do one of the following:
- Enter the absolute angle to which you want to rotate the object.
- Drag the object around its base point and specify a point location to which you want to align the object.
Modify toolbar: 
Command line equivalent: ROTATE