You can create a variety of curved objects with AutoCAD, including splines, helixes, circles, arcs, and ellipses. All curves are created on the XY plane of the current UCS.

To create a curve, you create a new instance of one of the following objects:

Arc

Creates an arc given the center point, radius, start and end angles.

Circle

Creates a circle given the center point and radius.

Ellipse

Creates an ellipse given the center point, a point on the major axis, and the radius ratio.

Spline

Creates a quadratic or cubic NURBS (nonuniform rational B-spline) curve.

Helix

Creates a 2D or 3D helix object.