## The Teaching of Geometry |

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algebra altitude ancient angles are equal applications Archimedes Aristotle attempt axioms basal base beginning bisect Book called century A.D. CHAPTER circle circumference congruent considered construction corollary cube curve cylinder define definition distance drawing easily edge elementary geometry etry Euclid Euclid's Elements example exercises fact figure geom given line Greek Heron of Alexandria hexagon illustration incommensurable inscribed interest intersect isosceles known locus mathematician mathematics means measure method modern octahedron parallel parallelepiped parallelogram perpendicular plane geometry Plato polyhedrons postulate practical prism problem Proclus proof proportion proposition proved pupil pyramid Pythagoras Pythagorean Theorem radius ratio reason regular polygons relating right angles right triangle segment sides solid geometry sphere square statement straight angle straight line surface syllabus tangent teacher teaching textbook Thales thing tion to-day trigonometry usually vertex vertices volume word writers

### Popular passages

Page 246 - Two triangles having an angle of the one equal to an angle of the other are to each other as the products of the sides including the equal angles.

Page 176 - IF a side of any triangle be produced, the exterior angle is equal to the two interior and opposite angles ; and the three interior angles of every triangle are equal to two right angles.

Page 137 - A circle is a plane figure contained by one line such that all the straight lines falling upon it from one point among those lying within the figure are equal to one another; 16 And the point is called the center of the circle.

Page 139 - ... 20. Of trilateral figures, an equilateral triangle is that which has its three sides equal, an isosceles triangle that which has two of its sides alone equal, and a scalene triangle that which has its three sides unequal.

Page 236 - If in a right triangle a perpendicular is drawn from the vertex of the right angle to the hypotenuse : I.

Page 221 - Magnitudes are said to have a ratio to one another which are capable, when multiplied, of exceeding one another.

Page 182 - If two triangles have two sides of the one equal, respectively, to two sides of the other, but the included angle of the first triangle greater than the included angle of the second, then the third side of the first is greater than the third side of the second.

Page 136 - But when a straight line, standing on another straight line, makes the adjacent angles equal to one another, each of the angles is called a right angle, and the straight line which stands on the other is called a perpendicular to it (Def.

Page 50 - Euclid's, and show by construction that its truth was known to us ; to demonstrate, for example, that the angles at the base of an isosceles triangle are equal...

Page 289 - If two angles not in the same plane have their sides respectively parallel and lying on the same side of the straight line joining their vertices, they are equal, and their planes are parallel. Let the corresponding sides of angles A and A' in the planes MN and PQ be parallel, and lie on the same side of AA'.