All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sidef. For any rectilineal figure ABCDE can be divided into as many triangles as the figure has sides, by drawing...
The Elements of Euclid: The Errors, by which Theon, Or Others, Have Long Ago ... - Page 35
by Robert Simson - 1806 - 518 pages
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