



 
Dale, Do you mean that the distance between a pair of parallel sides is 10 feet or the distance between two opposite vertices is 10 feet? Harley Dale wrote back Yes, I mean that the distance between a pair of parallel sides is 10 feet . Dale, In the diagram below the length of AC is 5 feet, the angle ABC has measure 144/2 = 72 degrees and the angle CAB is a right angle. The tangent of the angle ABC is CA = 5 feet divided by AB, thus
and thus
Hence the length of a side of the decagon is 2 × 1.62 = 3.24 feet. Harley Weston  


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