Mathematical principle of planar Z-plasty

To extend the work of precursors attempting to use Z-plasties with angles t hat have arbitrary degrees and may or may not be equal in size, a comprehen sive study was done to clarify and simplify the correlation among the angle s, limbs, and diagonals of the geometrical construction of Z-plasties. In g eometry, the truth of a proposition must be proved; it is a question to whi ch the answer must be found. By law and formula, a ternary trigonometric eq uation was derived from a simplified geometric diagram by a trigonometric a pproach. A procedure declaration accompanies this formula; neither was prev iously mentioned in the literature.