Elements of geometry : containing the first six books of Euclid, with a supplement on the quadrature of the circle, and the geometry of solids : to which are added, Elements of plane and spherical geometry (1826)
Playfair, John, 1748-1819, Euclid · Philadelphia : Marot & Walter · leaf 153
triangles BEF andCDF are equiangular, and there-fore BF : EF :: CF : FI) (4. fi.),^or alternately (16. 5.) BF : FC.. EF : FD. Since, then, the sides about the equal angles BFC,EFD are proportionals, the triangles BFC, EFD are also equiangular(6. 6.); wherefore the angle FCB is equal to the angle… … OF GEOMETRY. BOOK VI. 153 gles; therefore the remaininj^ angles AEF, FGC are also equal(32. 1.): But AEF is a ri ht angle, therefore FGC is a right angle,and AG is perpendicular to BC. Q. E. D. Cor. The triangle ADE is similar to Ihe triangle ABC. For thetwo triangles BAD, CAE having the angles at…
Euclid's Elements · Geometry · 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-100-221.webp)
![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-86-129.webp)
