You can use the Skew tab of the Transform dialog box to precisely skew a object by specifying the degree of skew. Open the Arrange menu, choose Transform, and choose Skew.
The Skew tab lets you skew a object based on its current shape. For example, if you skew a square 45 degrees and then type 45 to skew it another 45 degrees, the object is skewed on additional 45 degrees.