A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 88
ent to each other, the two sides not common tuillfaU in thesame straight line, Dem.—Let the sum of the two anglesBOA and COD be two right angles.Prolong CO, forming the angle DOE.Then is DOE supplemental to COD {131,133)f and hence equal to BOA, which issupplemental to COD by hypothesis.Now, if AOB… … PROPOSITION IV. 137. TJieorem.—If from a point withotit a straight line a per-pendicular he draivn, oblique lines from the same point cutting theline at equal distances from the foot of the perpendicular are equal toeach other; the angles which they form iDxth the perpendicular areequal to each…
Geometry · Trigonometry
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