# Constraints Defined in Dialogue Box Tool

There are many constraints that are available to use on your sketch, each with different functions.
Constraints are imposed onto sketches to ensure that the profile does not change when one of its dimensions is altered. Distance – the offset between 2 geometries Length – determines the length of specific geometry Angle – the angle between 2 selected elements Radius/Diameter – sets the radius and/or diameter of a circle/arc Semimajor axis – dimensions the length of the major axis of an ellipse Semiminor axis – dimensions the length of the minor axis of an ellipse Symmetry – makes sure the object is symmetrical about an axis selected. You have to select the 2 objects that will be in symmetry with one another first then select the axis of symmetry. Remember to hold the Ctrl key! Midpoint – constrains an existing point to the centre of a line Equidistant Point – moves an existing point to a position where it is the same point from existing geometry. The order in which the geometry is selected is important; first the two lines have two be selected before the point Fix – prevents the selected geometry from translating Coincidence – moves the objects so that they are in line Concentricity – moves the point to the centre of the circle Tangency – moves lines to make them tangential to existing geometry Parallelism – makes two lines parallel Perpendicular – makes two lines perpendicular Horizontal – Creates a line that is horizontal Vertical – Creates a line that is vertical 