 | 1903 - 692 страница
...uniformly. Casey (El. of Euclid, 8th ed., p. 299) says : " The discovery of the proposition that ' the sum of the three angles of a triangle is equal to two right angles ' is attributed to Pythagoras. Until modern times no proof of it, independent of the theory... | |
 | 1891 - 656 страница
...tests of other rational processes. This is true in mathematics. Thus, when once it is proven that the sum of the three angles of a triangle is equal to two right angles, no rational process can be accepted as true which in premise or conclusion contravenes this... | |
 | 1904 - 938 страница
...straight line joining their centers is the perpendicular bisector of their common chord. 6. Prove: The sum of the three angles of a triangle is equal to two right angles. 7. (a) Circumscribe a circle about a given triangle. (&) Inscribe a circle In a given triangle.... | |
 | George Albert Wentworth - 1904 - 496 страница
...equal angles are called homologous sides. BOOK I. PLANE GEOMETRY. PROPOSITION XVIII. THEOREM. 129. Tlie sum of the three angles of a triangle is equal to two right angles. ACF Let A, B, and BCA be the angles of the triangle ABC. To prove that ZA + ZB + Z BCA = 2... | |
 | Isaac Newton Failor - 1906 - 431 страница
...Scalene. f Isosceles. fc Oblique. Acute. Scalene. f Isosceles. . Obtuse. PROPOSITION XL THEOREM 153 The sum of the three angles of a triangle is equal to two right angles.* HYPOTHESIS. ABC is any triangle. CONCLUSION. PROOF Draw MN through B II to AC, and produce... | |
 | David Sands Wright - 1906 - 104 страница
...the bisectors of a pair of supplementary adjacent angles meet at an angle of 90°. 5. Theorem. The sum of the three angles of a triangle is equal to two right angles. 1. How many degrees in each angle of the triangle ABC, if they are in the proportion of 1,... | |
 | Isaac Newton Failor - 1906 - 440 страница
...Isosceles. 1 f Acute. -{ I Oblique. Scalene. f Isosceles. v. Obtuse. 82 PROPOSITION XI. THEOREM 153 The sum of the three angles of a triangle is equal to two right angles.* HYPOTHESIS. ABC is any triangle. CONCLUSION. ZA + ZB + ZC = 2rt. A. PROOF Draw MN through... | |
 | Benchara Branford - 1908 - 434 страница
...body of scientific theorems. Allman attributes to Thales the discovery of the two theorems — (a) The sum of the three angles of a triangle is equal to two right angles ; (&) The sides of equi-angular triangles are proportional. (Hence the basis of the theory of... | |
 | Trinity College (Dublin, Ireland) - 1909 - 546 страница
...the length of the perpendicular from an extremity of its base on the opposite side. 3. Prove that the sum of the three angles of a triangle is equal to two right angles. 4- If a straight line is divided into two parts, prove that the sum of the squares at the whole... | |
 | 1909 - 756 страница
...eloquently, and we can not stifle her voice. But our intellect also tells us, and with equal force, that the sum of the three angles of a triangle is equal to two right angles, and we are unable to rebel against its authority. If we see God behind the categorical imperative,... | |
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After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles... 
