| Washington (State). Superintendent of Public Instruction - 1904
...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.... | |
| 1891
...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... | |
| George Albert Wentworth - 1904 - 473 sider
...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 - 418 sider
...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... | |
| David Sands Wright - 1906 - 84 sider
...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
...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... | |
| Euclid, Sir Thomas Little Heath, Johan Ludvig Heiberg - 1908
...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, George Parker Bidder - 1908 - 392 sider
...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... | |
| 1909
...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,... | |
| Wilbur Fisk Nichols - 1910
...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?... | |
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