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A prerequisite for this tutorial is that you have done the Draw a Circle tutorial and have saved the drawing in a file circle_1.svg.

1. Open a new document in Drawmetry by clicking on the New button in the File tool bar or selecting New from the File menu.
2. Use Include from the file menu to include the file circle_1.svg into this drawing. This adds a circle and its two anchor point variables into the drawing. For the remainder of this tutorial we ar assuming that P_0 is the anchor point variable at the center of the circle and P_1 is the anchor point variable on the circle. If that is not the case, substitute references to these point variables by their actual names in the rest of this tutorial.
3. Enter Insert Point mode and add another point variable. We use P_2 to reference this point variable.
4. Enter Default mode and select the point variable P_2. In the constraint field type: "=rotate(P_0, P_1, pi/2)" and type Enter or Return. P_2's marker should become red and located such that the angle P_1 P_0 P_2 is 90 degrees (i.e., pi/2 radians) going counter-clockwise and at the same distance from P_0 as P_1.
5. Select the circle and modify the anchor constraint in the constraint field to "=anchor(P_0, P_1, P_2)".
6. Select P_2, and modify the constraint in the constraint field to "=angle(P_0, P_1, pi/2). Notice that P_2 can be dragged along a line that is perpendicular to P_0 P_1 and that the circle deforms into an ellipse while doing so. Save the drawing as ellipse_1.svg into the Basic Shapes folder.
7. Sometimes it may be useful to have the axes of an ellipse aligned with the horizontal and vertical directions. Select P_1, and add the constraint: "= horizontal(P_0)". Save the drawing as ellipse_2.svg into the Basic Shapes folder.