Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 23. Could you, from a point without a line, by means of angles, draw a parallel to the line ? Explain how. Would a transversal help you to do it ? How ? IV. TRIANGLES. 1. The Angles Of Triangles. 1. Draw a triangle, and on the circumference of a circle determine the sum of its angles. 2. If one of the angles of a triangle were enlarged, what effect would the change have upon the other angles ? 3. If two of its angles were enlarged, how would it affect the third? In either case, would the sum of the angles be changed ? What general conclusion may therefore be drawn concerning the sum of the three angles of a triangle? 4. If two of the angles of a triangle are 65 and 52, 27 and 74, or 85 and 89, what is the third angle ? 5. How many angles of 90 (right angles) can a triangle contain ? Draw such a triangle, and designate it abc, by writing one of these letters at the vertex of each angle. Which sides include the right angle ? How do these sides meet each other ? 6. Name the side opposite the right angle. This side is the hypotenuse. 7. Which is the longest side in every right-angled triangle ? 8. What is the sum of the angles at the hypotenuse ? What kind of angle is each of them ? 9. How many degrees in one of the angles at the hypotenuse, when the other is 29, 40, 67, or 71? 10. How many obtuse angles can a triangle have ? 11. Draw a triangle containing an obtuse angle. 12. In such a triangle, which of the sides, according to length, lies opposite the obtuse angle ? 13. How does the sum of the angles at the longest side compare with 90 ? What kind of angle, therefore, is each of them ? 14. If the obtuse angle and one of the acute angles are 115 and 22, 104 and 35, or 129 and 31, what is the third angle ? 15. From a point without a li...