Equal Length/Radius/Angle

This constraint forces two lengths, angles, or radiuses to be equal.

The equal-angle constraint requires four vectors as input: the two equal angles are the angle between each pair of inputs. For example, select line segments A, B, C, and D. The constraint forces the angle between lines A and B to be equal to the angle between lines C and D. If the wrong supplementary angle is chosen, then choose Constrain → Other Supplementary Angle, as for the angle constraint.

If a line and an arc of a circle are selected, then the length of the line is forced equal to the length (not the radius) of the arc.