ویدئو شماره 83

To set a 180-degree angle in on or more points from a piece, select the piece’s point(s) to be set at this angle, and, in the Context bar, click on Set angle 180°.

There is a single tangent on the smooth point. This tangent has two control points whose movements are symmetrical. If the point separates a curve from a line, then the control point from the curve side can move only along the line, so the corner remains smooth.