Tool Palettes Curves > Lines (Tangent) > Line perpendicular to curve > To draw a line perpendicular to a curve

Curves > Lines (Tangent) > Line perpendicular to curve

Allows you to draw a keypoint line perpendicular to an existing curve.

To draw a line perpendicular to a curve

Click the Curves > Lines (Tangent) > Line perpendicular to curve icon, or choose Lines (Tangent) > Line perpendicular to curve from the Curves palette menu.
Click the start point of the perpendicular line.
Click the curve you want the line to be perpendicular to.

The Line perpendicular to curve tool calculates the end point for the line to be perpendicular to the curve.

If it cannot find a perpendicular, it extends the ends of the curve.
If it finds more than one perpendicular, it uses the perpendicular closest to where you clicked.

To get a true 3D tangent, use the Line tool with curve snapping to place the first point on the curve, then snap to the tangent guideline.

The tangent lines are tangent in the current view. It is only a true 3D tangent when the curve and start point are planar.

In an orthographic window, the perpendicular is relative to the view. In a perspective window, it is a 3D perpendicular.

Do not use the tangent line tools in the perspective window.