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94 | Chapter 7 Constraining Sketches
Applying Dimension Constraints
It is good practice to stabilize the shape of a sketch with geometric constraints
before you specify size with dimensional constraints.
Dimensions specify the length, radius, or rotation angle of geometric elements
in the sketch. Unlike geometric constraints, dimensions are parametric;
changing their values causes the geometry to change.
Dimensions can be shown as numeric constants or as equations. Although
you can use them interchangeably, they each have specific uses.
■ Numeric constants are useful when a geometric element has a static size
and is not related to any other geometric element.
■ Equations are useful when the size of a geometric element is proportional
to the size of another element.
In the following illustration, all of the lines and the angles are constant, and
stated as numeric values.
In the next illustration, the dimensions are expressed as equations.