Drawing Arcs Based on Points. Autodesk AUTOSKETCH 8

An ellipse is a closed curve that resembles a flattened circle. Mathematically, the path of a point that moves so the sum of the distances from it to a pair of fixed points remains constant. You can draw an ellipse by specifying any of the following:

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A rectangle using two points (in which an ellipse is tangent to all four sides)

Major and minor axes using three points

Tools for drawing arcs and circles can be accessed from the Draw menu or the

Arcs & Circles toolset on the All-In-One toolbar. You can also activate the Arc or Circle toolbars (which contain the same commands but can be docked anywhere onscreen) by right-clicking a bar, then clicking Toolbars on the pop-up menu that appears. Simply check Arc or Circle, then click OK to make the Arc or Circle toolbar visible onscreen.

Drawing Arcs Based on Points

The Draw menu has three commands for drawing arcs based on points. Two of the commands, 3 Points and 2 Points & Center, have modifier keys. In each case, pressing CTRL as you enter the third point switches the second and third points. Instead of entering the startpoint, endpoint, and a point along the arc, for instance, you can enter the startpoint, a point along the arc, then, while pressing CTRL, enter the endpoint.

To draw an arc by specifying its endpoints and a third point

1 On the Draw menu, click Arc, 3 Points, or click the 3 Points Arc button on the All-In-One toolbar.

2 Click the startpoint. A small diamond marks the point.

3 Click a second point. Another diamond marks this point and a rubberband arc appears and follows the pointer.

4 Click the endpoint or press CTRL and click a point along the arc.

Drawing Arcs Based on Points

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To draw an arc by specifying its endpoints and the centerpoint

1 On the Draw menu, click Arc, 2 Points & Center, or click the 2 Points &

Center Arc button on the All-In-One toolbar.

2 Click the startpoint. A small diamond marks the point.

3 Click a second point. Another small diamond marks the point.

4 Click the centerpoint or press CTRL to click the endpoint.

To draw an arc by specifying its endpoints and included angle

1 On the Draw menu, click Arc, 2 Points & Angle, or click the 2 Points &

Angle button on the All-In-One toolbar.

2 Enter the included angle on the edit bar and press ENTER.

3 Click the startpoint. A small diamond marks the point and a rubber-band arc appears.

4 Click the endpoint.

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Chapter 13 Arcs & Circles