Books Books An exterior angle of a triangle is equal to the sum of the two opposite interior angles. Junior High School Mathematics ... - Page 29
by Edson Homer Taylor, Fiske Allen - 1923 ## Syllabus of Geometry

George Albert Wentworth - Geometry - 1896 - 50 pages
...equiangular triangle, each angle is one-third of two right angles, or two-thirds of one right angle. 145. The exterior angle of a triangle is equal to the sum of the two opposite interior angles. 146. Cor. The exterior angle of a triangle is greater than either of the opposite interior angles.... ## Elements of Geometry

Andrew Wheeler Phillips, Irving Fisher - Geometry - 1897 - 366 pages
...B. §70 [Being base angles of an isosceles triangle.] , But angle »= angle A + angle B. § 58 [The exterior angle of a triangle is equal to the sum of the two opposite interior angles. Substituting A for B, n = 2A. But n is measured by arc B.£. § 185 Hence half of «, or A, is measured... ## Elements of Geometry

George Washington Hull - Geometry - 1897 - 408 pages
...Substituting Z A for Z a, and Z C for Z c, we have Z v4 + Z d + ZC= two right angles. QED 49. COR. 1.—An exterior angle of a triangle is equal to the sum of the two opposite interior angles. 50. COR. 2.—An exterior angle of a triangle is greater than either of the opposite interior angles.... ## Elements of Analytic Geometry

Joseph Johnston Hardy - Geometry, Analytic - 1897 - 398 pages
...Two angles whose sides are perpendicular, each to each, are either equal or supplementary. 13. The exterior angle of a triangle is equal to the sum of the two opposite interior angles. 14. Two right angles are equal if the hypotenuse and an acute angle of one are equal respectively to... ## Elements of Geometry

Andrew Wheeler Phillips, Irving Fisher - Geometry - 1897 - 376 pages
...angle BXD is measured by one-half the sum of the arcs BDa.ndAC. Join A and D. Now m — s + ze. § 58 [An exterior angle of a triangle is equal to the sum of the opposite interior angles.] But angle s is measured by ^ arc BD. § 189 And angle w is measured... ## Elements of Geometry

Andrew Wheeler Phillips, Irving Fisher - Geometry - 1897 - 374 pages
...angle BXD is measured by one-half the sum of the arcs BD and AC. Join A and D. Now w — s + w. § 58 [An exterior angle of a triangle is equal to the sum of the opposite interior angles.] But ' angle J is measured by ^ arc BD. § 189 And angles is measured... ## The Essentials of Geometry (plane)

Webster Wells - 1898 - 264 pages
...85. Cor. I. It follows from the above demonstration that Z.BCD = Z.ECD + Z.BCE = ZA + ZB; hence 1. An exterior angle of a triangle is equal to the sum of the two opposite interior angles. 2. An exterior angle of a triangle is greater than either of the opposite interior angles. 87. Cor.... ## Essentials of Geometry (plane).

Webster Wells - Geometry - 1898 - 250 pages
...Cor. I. It follows from the above demonstration that Z BCD = Z EC/) + Z BCE = ZA + ZB; hence 1. .<4n exterior angle of a triangle is equal to the sum of the two opposite interior angles. 2. An exterior angle of a triangle is greater than either of the opposite interior angles. 86. Cor.... ## Plane and Solid Geometry

George Albert Wentworth - Geometry - 1899 - 496 pages
...COR. 7. In an equiangular triangle, each angle is one third of two right angles, or 60°. 137. COR. 8. An exterior angle of a triangle is equal to the sum of the two opposite interior angles, and therefore greater than either of them. PROPOSITION XIX. THEOREM. 138. The sum of two sides of a... 