#Arc

Key A. Three ways, the switch is in the top bar.

• Centre — start — end: the first click sets the centre, the second the start, the third the end.
• By three points: start, end and a point on the arc.
• Tangent: an arc continuing the chosen segment without a kink.

#An arc is held by constraints

Tangency between an arc and a neighbouring segment is a real constraint: move the segment and the arc stays tangent instead of splitting at the joint. The radius takes part in the solve as well, so equal radii and point-on-arc work just as they do for a circle.

#A hint

Rounding a corner in a sketch is easier with the Corner fillet tool (click the corner of two lines): it places the arc and both tangencies for you.