 | George Anthony Hill - Geometry - 1888 - 202 pages
...construct after we have found the values of three other parts by direct measurement. LESSONS IN GEOMETRY. Lesson 31. 1. How can it be shown to the eye that...the triangle will just make a straight angle at D. FIG. 65. 2. Prove that the sum of the angles of every triangle is equal to 180°. Draw any triangle... | |
 | George Anthony Hill - 1891 - 206 pages
...direct measurement. LESSONS IN GEOMETRY. Lesson 31. 1. How can it lie shown to the eye tluit the sum of the angles of a triangle is equal to a straight...the triangle will just make a straight angle at D. I) FIG. 64, B B Fid. 65. 2. Prove tliat the sum of the angles of every triangle is equal to 180°.... | |
 | George Anthony Hill - Geometry - 1894 - 200 pages
...construct after we have found the values of three other parts by direct measurement. LESSONS IN GEOMETRY. Lesson 31. 1. How can it be shown to the eye that...triangle is equal to a straight angle, or 180°? Draw a triangle'^5O (Fig. 64) and the altitude CD. Cut out the triangle, and fold the corners over the dotted... | |
 | Arthur Schultze, Frank Louis Sevenoak - Geometry - 1902 - 394 pages
...of the first must be parallel to the third side of the second. PROPOSITION XII. THEOREM 93. The sum of the angles of a triangle is equal to a straight angle. B Hyp. ABC is a triangle. To prove ZA -f- ZB + ZC = a st. Proof. Draw line Z>£? || BC through A. ZB=.... | |
 | Arthur Schultze, Frank Louis Sevenoak - Geometry - 1901 - 394 pages
...of the first must be parallel to the third side of the second. PROPOSITION XII. THEOREM 93. The sum of the angles of a triangle is equal to a straight angle. B ------ c Hyp. ABC is a triangle. To prove ZA + ZB + ZC = a st. Z. Proof. Draw line DE || BC through... | |
 | Arthur Schultze, Frank Louis Sevenoak - Geometry - 1901 - 396 pages
...of the first must be parallel ti the third side of the second. PROPOSITION XII. THEOREM 93. Tfie sum of the angles of a triangle is equal to a straight angle. B Hyp. ABC is a triangle. To prove ZA + ZB + ZC= a st.Z. Proof. Draw line DE || BC through A. . (Ax.... | |
 | Arthur Schultze - 1901 - 260 pages
...of the first must be parallel to the third side of the second. PROPOSITION XII. THEOREM 93. The sum of the angles of a triangle is equal to a straight angle. B Hyp. ABC is a triangle. To prove ZA + ZB Proof. Draw line DE l BC through A. . (Ax.2.) But £A +... | |
 | Arthur Schultze, Frank Louis Sevenoak - Geometry - 1913 - 490 pages
...are parallel to MN and PQ respectively. TRIANGLES —PART II PROPOSITION XXII. THEOREM 110. The sum of the angles of a triangle is equal to a straight angle. DGiven A ABC. To prove STATEMENTS Through A draw DE II BC. But z 2 = za = a st. Z. Proof t. Z. REASONS... | |
 | Arthur Schultze, Frank Louis Sevenoak - Geometry, Plane - 1913 - 328 pages
...parallel to MN and PQ respectively. v^ TRIANGLES —PART II PROPOSITION XXII. THEOREM 110. The sum of the angles of a triangle is equal to a straight angle. DGiven A ABC. To prove ZB + Z C= a st. Z. Proof STATEMENTS Through A draw DE II BC. Zl = Zs. Z 2 =... | |
 | Edith Long, William Charles Brenke - Geometry, Modern - 1916 - 292 pages
...side of a regular hexagon inscribed in a circle; of a nonagon; of a pentagon. 11. Prove that the sum of the angles of a triangle is equal to a straight angle by inscribing it in a circle. 12. Prove similarly that the opposite angles of an inscribed quadrilateral... | |
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How can it be shown to the eye that the sum of the angles of a triangle is equal to a straight angle, or 180°? 
