Curved objects are arcs, circles, polyline arcs, donuts, ellipses, and splines.
To create an arc, you can specify various combinations of center, endpoint, start point, radius, angle, chord length, and direction values.
To create circles, you can specify various combinations of center, radius, diameter, points on the circumference, and points on other objects.
A polyline is a connected sequence of line segments created as a single object. You can create straight line segments, arc segments, or a combination of the two.
Donuts are filled rings or solid-filled circles that actually are closed polylines with width.
The shape of an ellipse is determined by two axes that define its length and width. The longer axis is called the major axis, and the shorter one is the minor axis.
A spline is a smooth curve that passes through or near a given set of points. You can control how closely the curve fits the points.
A helix is an open 2D or 3D spiral.