Edit Curves > Extend > Extend Curve

Edit Curves > Extend > Extend Curve >

Extend Method: Distance lets you enter a value for the length of the Extension Type.

Point extends to a world space position you specify in Point To Extend To.
Extension Type: Linear extends the curve in a straight line:

Circular extends the curve as an arc:

Extrapolate maintains the tangent of the selected curve.
Extend Curve At: Start extends the curve from its start point.

End extends the curve from its end point.

Both extends the curve at both ends.
Join to Original: Attaches the curve extension to the original curve. If off, the input curve and the curve extension are independent objects. You can transform the extension separately.
Remove Multiple Knots: Removes the multiple knots that Maya creates when Join To Original is turned on.
Keep Original: Keeps the original curve after the extension is created. If both Keep Original and Join to Original are off, the extension curve replaces the original curve.
Input Curve: Input Curve information is read-only. It gives you access to the input curve you extended. Click the arrow button to select the curve and open that section of the Attribute Editor.
Input Point: This is the same as Point To Extend To in the options window.