Modifying both direction and magnitude of the tangent vector

To modify both the magnitude and the direction of the tangent vector of a curve in a certain point, start the Curve Shape Constraint command and proceed as follows.

1	Select the curve by clicking on the location you want to edit. A handle will be displayed on the curve in the location you selected.
	You are now enabled to change the curve shape by moving the location you selected on it or by modifying the tangency conditions in the same location.
2	To modify the tangent vector magnitude and its direction proceed as follows:

• Right-click on the tangent vector and select Set Tangent. The handle starts moving along as you move the mouse. Click in the position defining the new desired direction and magnitude for the vector.
  
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• Click on the tangent vector close to one of its end point. The handle starts moving along as you move the mouse while holding down the mouse button. Release the mouse button in the position defining the new desired direction and magnitude for the vector.