Constraint-based Drawing

Constraint-based Drawing

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A constraint-based approach starts with a drawing that contains all the pertinent geometrical objects, but does not at first require them to be correctly related (though the circle should lie more or less inside the triangle to distinguish it from the excircles):

 

All we know of the incircle is that it is tangent to all three sides of the triangle. So we describe the problem by applying…

  1. …the first tangency constraint:

 

  1. …the second tangency constraint:

 

  1. …and the last:

 

The drawing now accurately represents the desired situation.