Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 34
angle. Cor. 2. If the sum of two of the tour angles be equal to tworight angles, the sum of the remaining two will also be equallo two right angles. Cor. 3. Since all the angles of a square or rectangle, areequal to each other (Def. 48), and their sum equal to fourright angles, it follows that each… … Let ABCDE be any polygon: then willthe sum of its inward angles A+B+C+D+Ebe equil to twice as many right angles,wanting four, as the figure has sides. For, from an} point P, within the poly- A B gon, draw the lines PA, PB, PC, PD, PE, to each cf theangles, dividing the polygon into as many…
Geometry · Plane trigonometry
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![An illustration from Divina proportione : opera a tutti glingegni perspicaci e curiosi necessaria oue ciascun studioso di philosophia: prospettiua pictura sculptura: architectura: musica: e altre mathematice: suavissima: sotile: e admirabile doctrina consequira: e delecterassi: co[n] varie questione de secretissima scientia (1509)](https://img.insideoutlibrary.com/img/200/ia-divinaproportion00paci-56-88.webp)
