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An exterior angle of a triangle is equal to the sum of the two opposite interior angles.
Junior High School Mathematics ... - Page 25
by Edson Homer Taylor, Fiske Allen - 1923

## Schultze and Sevenoak's Plane and Solid Geometry

Arthur Schultze, Frank Louis Sevenoak - Geometry - 1913 - 486 pages
...The altitudes upon the arms of an isosceles triangle are equal. 60 PROPOSITION XXIII. THEOREM 117. An exterior angle of a triangle is equal to the sum of the two remote interior angles. cw Given the ext. Z ACD of A ABC. To prove Z ACD = ZA + Z B. HINT....

## Schultze and Sevenoak's Plane Geometry

Arthur Schultze, Frank Louis Sevenoak - Geometry, Plane - 1913 - 328 pages
...272. The altitudes upon the arms of an isosceles triangle are equal. PROPOSITION XXIII. THEOREM 117. An exterior angle of a triangle is equal to the sum of the two remote interior angles. B A Given the ext. Z ACD of A ABC. C To prove' Z ACD = Z A + Z B. HINT....

## Robbin's New Plane Geometry

Edward Rutledge Robbins - Geometry, Plane - 1915 - 282 pages
...the other vertices are the opposite interior angles. [ZA and Z C.] PROPOSITION XXXIII. THEOREM 102. An exterior angle of a triangle is equal to the sum of the opposite interior angles. Given : A ABC ; exterior Z ABD. To Prove : Z ABD = ZA + Z C. ^" ~ ""...

## Plane Geometry

Claude Irwin Palmer, Daniel Pomeroy Taylor - Geometry, Plane - 1915 - 336 pages
...two right angles. Prolong AC to F . Draw CE II AB. ZA = Zz. § 133 § 132 §60 §111 144. Theorem. An exterior angle of a triangle is equal to the sum of the opposite interior angles, and is therefore greater than either of them. §105 Why? .-. ZBCF > ZA...

## Plane Geometry

John Wesley Young, Albert John Schwartz - Geometry, Modern - 1915 - 248 pages
...of the triangle. Thus ' 73 C "^ DCA (Fig. 73) is an exterior angle of PLANE GEOMETRY 186. THEOREM. An exterior angle of a triangle is equal to the sum of the opposite interior angles. D FIG. 74. (The proof is left to the student.) 187. COBOLLABY. An exterior...

## Plane and Solid Geometry

William Betz - Geometry - 1916 - 536 pages
...+ Zq Ax. 2 4. But Zp + Z o + Z q = a st. Z. Why ? .-.Zm + Zo + Zn = ast. Z. Ax. 1 181. COROLLARY 1. An exterior angle of a triangle is equal to the sum of the two remote interior angles, and is therefore greater than either of them. 182. COROLLARY 2. If...

## Third-year Mathematics for Secondary Schools

Ernst Rudolph Breslich - Logarithms - 1917 - 408 pages
...384. The sum of the exterior angles of a triangle, taking one at each vertex, is 360°. (115) 385. An exterior angle of a triangle is equal to the sum of the two remote interior angles. (118), (199) 386. If the angles of one triangle are respectively equal...

## Junior High School Mathematics, Book 3

George Wentworth, David Eugene Smith, Joseph Clifton Brown - Mathematics - 1918 - 296 pages
...an exterior angle of A ABC, and /A and /C are called the opposite interior angles. AQ •"• 106. COROLLARY. An exterior angle of a triangle is equal to the sum of the two opposite interior angles. For /XBC + / CBA = a st. /, and ^ A + / C + / CBA = a st. /^ Therefore / A + / C + / CBA = / XBC +...