To rotate the Page View
Choose View > Page View > Rotate View and choose Clockwise or Counterclockwise in the drop-down list.
Notes
You can change the page view in 90-degree steps. This does not change the document itself, it is just a different viewing mode.
To really rotate page images in 90-degree steps, choose Pages in the Panel bar, right click, choose Rotate and specify which pages to rotate. See Page Operations.
You can rotate objects on a PDF page by 45 degree steps using a shortcut menu, or perform free rotation with the object handle. The objects really are rotated. See the Edit Object Tool.