# Robbin's New Plane Geometry

American Book Company, 1915 - Geometry, Plane - 264 pages

### Contents

 ANGLES 2 EXERCISES 9 THEOREMS AND DEMONSTRATIONS 15 PARALLEL LINES 21 QUADRILATERALS 47 POLYGONS 60 CONCERNING ORIGINAL EXERCISES 68 THE CIRCLE 75
 ORIGINAL EXERCISES 109 ORIGINAL EXERCISES ON LOCI 115 AREAS 138 THEOREMS AND DEMONSTRATIONS 193 FORMULAS 207 CONSTRUCTION PROBLEMS 213 REGULAR POLYGONS CIRCLES 225 ORIGINAL EXERCISES THEOREMS 239

 SUMMARY 94 KINDS OF QUANTITIES MEASUREMENT 96
 FORMULAS 245 INDEX 261

### Popular passages

Page 38 - The perpendicular bisectors of the sides of a triangle meet in a point. 12. The bisectors of the angles of a triangle meet in a point. 13. The tangents to a circle from an external point are equal. 14...
Page 32 - The sum of two sides of a triangle is greater than the third side, and their difference is less than the third side.
Page 144 - If the product of two quantities is equal to the product of two others, one pair may be made the extremes, and the other pair the means, of a proportion.
Page 239 - An equilateral polygon circumscribed about a circle is regular if the number of its sides is odd.
Page 152 - If a line divides two sides of a triangle proportionally, it is parallel to the third side.
Page 53 - The line joining the mid-points of two sides of a triangle is parallel to the third side, and equal to half the third side.
Page 41 - If two triangles have two angles of the one equal to two angles of the other, each to each, and one side equal to one side, viz.
Page 173 - In any triangle, the square of the side opposite an acute angle is equal to the sum of the squares of the other two sides, minus twice the product of one of these sides and the projection of the other side upon it.
Page 4 - The straight lines are called the sides of the triangle, and their points of intersection are the vertices of the triangle.
Page 252 - The area of a regular inscribed hexagon is a mean proportional between the areas of the inscribed and circumscribed equilateral triangles. Ex.