E601  De symptomatibus quatuor punctorum, in eodem plano sitorum
(English Translation of Title)
Summary:
Euler uses the facts that given four points in the plane, A, B, C and D, they can either form a quadrilateral or a triangle with the fourth point on the interior and that knowing which of these and knowing five of the six distances between points, the sixth distance is determined, to show how to find relations among the angles, like sin A. Euler does the same thing knowing a quadrilateral is inscribed in a circle.
According to the records, it was presented to the St. Petersburg Academy on March 16, 1775.
Publication:

Originally published in Acta Academiae Scientarum Imperialis Petropolitinae 6, 1786, pp. 318

Opera Omnia: Series 1, Volume 26, pp. 258  269
 Extract printed in Arch. der Math. 26, 1856, pp. 335336 (Grunert) [E601a]
Documents Available:
 Original Publication: E601
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