 | William Weller Strader, Lawrence D. Rhoads - Geometry, Plane - 1927 - 434 pages
...angles are equal. 8. In an isosceles triangle the angles opposite the equal sides are equal. 9. The sum of the angles of a triangle is equal to a straight angle. Exercises. Informal Proofs In each of the following exorcisas state the hypothesis, the conclusion,... | |
 | Jean Piaget - Child development - 1928 - 282 pages
...is often the case in mathematics, and so lead from the particular to the universal. For in order to prove that the sum of the angles of a triangle is equal to 180° we work on a single triangle, and only afterwards do we generalize about all triangles by modifying... | |
 | Howard Whitley Eves - History - 1983 - 292 pages
...interior angles formed by a transversal cutting a pair of parallel lines, prove the following: (a) The sum of the angles of a triangle is equal to a straight angle. (b) The sum of the interior angles of a convex polygon of n sides is equal to n — 2 straight angles.... | |
 | Howard Whitley Eves - Mathematics - 1997 - 370 pages
...angles. 1.s.9 Assuming (i) A central angle of a circle is measured by its intercepted arc, (2] The sum of the angles of a triangle is equal to a straight angle, (3) The base angles of an isosceles triangle are equal, (4) A tangent to a circle is perpendicular... | |
 | A. E. E. McKenzie - Science - 1960 - 414 pages
...that, at the age of 12, Blaise was found by his father drawing diagrams on the floor and trying to prove that the sum of the angles of a triangle is equal to two right angles. He had invented his own terms, calling a straight line a bar and a circle a round,... | |
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The sum of the angles of a triangle is equal to a straight angle. 
