This diagram demonstrates the result of using 4 isoceles triangles, instead of the arcs of intersecting circles, as guidelines for Template A.
The dashed red line represents the latter approach, which is what is proferred in the Broug Islamic Patterns book we’re using in this sequence of examples.
If you expand the pen (hit <ctrl>+ on your browser) and observe, say, the upper left quadrant, you will see that the colored arcs hug the rectangle’s upper perimeter for a few pixels before rising to intersect.
In my next post, I will use simple geometry and trig to calculate the exact point of intersection between the rectangle’s upper perimeter and the dashed red line.
(hint: think fish liver)
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