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Историческую версию ChordCalc можно получить на Android
Вычисляет длину хорды
This application calculates the chord length for equi-spaced points on a circle.This chord length is used in engineering,when the user needs to mark off equi-spaced holes on a P.C.D in order to drill bolt hole patterns.The user enters the value for the P.C.D and the value for the number of holes and the chord length value is the output.