Create and Modify the Arc

We begin by drawing an arc and a straight construction line that form the perimeter around the top of the left conic portion.

1. Expand the Planes branch of the browser (tree view), right-click the Plane 1 < XY(+Z) > heading, and select Sketch.
2. Click Draw Draw Arc Center and Endpoints.
   1. Press Enter to define the origin as the center of the arc.
   2. Type -20 in the Y field and press Enter to specify the point (0, -20, 0) as the first endpoint of the arc.
   3. Type 20 in the Y field and press Enter to specify the point (0, 20, 0) as the second endpoint of the arc.
   4. Click Apply.
   5. Press Esc to exit the circle command.
3. Click View Navigate Enclose (Fit All). The arc should appear as shown below.

   

   Note: This arc orientation is necessary if we are to mirror the resulting half-structure about the YZ plane. The structure we are building is shown in the half-model image below (with the arc just created highlighted). Note that the structure is symmetrical about the YZ plane.

   

4. Click Draw Draw Line.
   1. Click one endpoint of the arc, then click the opposite endpoint of the arc. A padlock cursor appears when near an endpoint, indicating that the line will be snapped to the point.
   2. Press Esc twice to exit the line command.
5. Right-click the Plane 1 < XY(+Z) > heading under the Planes heading in the browser and deselect Sketch.

   The model should display as shown in the following image.  

   

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