The normal elementary geometry : embracing a brief treatise on mensuration and trigonometry : designed for academies, seminaries, high schools, normal schools, and advanced classes in common schools (1884)
Brooks, Edward, 1831-1912 · Philadelphia : Christopher Sower Co. · leaf 168
fourright angles (B. V. Th. XIII.) ; hence the sumof the arcs which measure them is less than the circumferenceof a great circle, which is the measure of four right angles.Therefore, etc THEOKEM IV. If a diameter of a sphere be drawn perpendicular to the plane ofany circle of the sphere, its… … The diameter AB, being perpendicular to the plan* of CFD,must pass through the centre E,since the diameter CD is a chordof the great circle ADBC, andmust therefore be bisected by adiameter perpendicular to it (B.IV. Th. III.). If arcs of great cir-cles A C, AF, and AD be drawnfrom A to different…
Geometry · Plane trigonometry
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![An illustration from Cosmographia Francisci Mavrolyci Messanensis Sicvli : in tres dialogos distincta, in quibus de forma, situ numerʹoq[ue] tam coelorum q[uam] elementorum, alijsq[ue] rebus ad astronomica rudimenta spectantibus satis disseritur (1543)](https://img.insideoutlibrary.com/img/200/ia-cosmographiafran00maur-128-0.webp)
