an be given as 88° and 95°. All three angles must sum up to 180, and we're already 3 degrees over balance. Or maybe the user specifies three edge-lengths: 21, 12 and 8. 21 is bigger than 12+8, so even if the triangle was stretched flat, the two short edges cannot reach the ends of the long edge. The above is easy to test for and I add errors to the component if an invalid triangle is provided. However there are also many angle+edge length combinations which result in invalid triangles.
I could of course test for these as well, but the problem is now tolerance. What if the user specifies a redundant angle of 54.7°, whereas the mathematics tell us that the actual angle is 54.7002°. Is that an error? If so, is the angle wrong or is perhaps one of the edges wrong? Or has the triangle simply been over-constrained? Is there a mathematically robust way of dealing with this? And if so, would that also be the most user-friendly way of dealing with it?…
Added by David Rutten at 2:23pm on August 23, 2014