| Isaac Newton Failor - Geometry - 1906 - 431 pages
...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 - Geometry - 1906 - 104 pages
...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,... | |
| Euclid - Mathematics, Greek - 1908 - 550 pages
...to the bearing of these propositions upon Euclid's Postulate 5 ; and the next theorem is VII. If the **sum of the three angles of a triangle is equal to two right** angles, through any point in a plane there can only be drawn one parallel to a given straight line.... | |
| Benchara Branford - Arithmetic - 1908 - 434 pages
...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... | |
| Electronic journals - 1909 - 756 pages
...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,... | |
| Trinity College (Dublin, Ireland) - 1909 - 546 pages
...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... | |
| James Joseph Sylvester - Mathematics - 1909 - 712 pages
...the degree to which (x - a) rises in the denominator of fx. t Take as an example the theorem that the **sum of the three angles of a triangle is equal to two** right-angles : as soon as by a stroke of the imagination a line is conceived as drawn from one angle... | |
| George Albert Wentworth, David Eugene Smith - Geometry, Plane - 1910 - 287 pages
...side of the transversal are supplementary, the lines are parallel. PROPOSITION XIX. THEOREM 107. The **sum of the three angles of a triangle is equal to two right** angles. c Given the triangle ABC. Y To prove that Z .4 + Z 7?+ Z (7 = 2 rt. A. Proof. Suppose BY drawn... | |
| Wilbur Fisk Nichols - 1910 - 236 pages
...a triangle. With your protractor measure each angle. Add the sum. What is the result? 8. Learn: The **sum of the three angles of a triangle is equal .to two right** angles, or 180°. 9. Can you draw a triangle that shall contain an acute, an obtuse, and a right angle?... | |
| Geometry, Plane - 1911 - 192 pages
...arcs, supplementary angles, incommensurable magnitudes, similarly divided lines. 2. Prove that the **sum of the three angles of a triangle is equal to two right** angles. 3. Complete and prove the following statement: The sum of the squares on two sides of a triangle... | |
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