Euclid's Elements of Geometry: Chiefly from the Text of Dr. Simson, with Appendix by Thos. Kirkland. the first six books |
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Page 29
... twice as many right angles as the figure has sides . D A B For any rectilineal figure ABCDE can be divided into as many triangles as the figure has sides , by drawing straight lines from a point F within the figure to each of its angles ...
... twice as many right angles as the figure has sides . D A B For any rectilineal figure ABCDE can be divided into as many triangles as the figure has sides , by drawing straight lines from a point F within the figure to each of its angles ...
Page 30
... twice as many right angles as the figure has sides ; therefore all the angles of the figure together with four right angles , are equal to twice as many right angles as the figure has sides , COR . 2. All the exterior angles of any ...
... twice as many right angles as the figure has sides ; therefore all the angles of the figure together with four right angles , are equal to twice as many right angles as the figure has sides , COR . 2. All the exterior angles of any ...
Page 56
... twice from the trapezium , which would appear to be impossible , if the sense in which Euclid applies the third axiom , is to be retained here . It may be observed , that the two parallelograms exhibited 56 EUCLID'S ELEMENTS .
... twice from the trapezium , which would appear to be impossible , if the sense in which Euclid applies the third axiom , is to be retained here . It may be observed , that the two parallelograms exhibited 56 EUCLID'S ELEMENTS .
Page 74
... twice the angle BAC . 11. From the extremities of the base of an isosceles triangle straight lines are drawn perpendicular to the sides , the angles made by them with the base are each equal to half the vertical angle . 12. A line drawn ...
... twice the angle BAC . 11. From the extremities of the base of an isosceles triangle straight lines are drawn perpendicular to the sides , the angles made by them with the base are each equal to half the vertical angle . 12. A line drawn ...
Page 77
... twice the same , but greater than two - thirds of the lines drawn through the point to the opposite sides . 44. In a plane triangle an angle is right , acute or obtuse , ac- cording as the line joining the vertex of the angle with the ...
... twice the same , but greater than two - thirds of the lines drawn through the point to the opposite sides . 44. In a plane triangle an angle is right , acute or obtuse , ac- cording as the line joining the vertex of the angle with the ...
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Common terms and phrases
A₁ ABCD AC is equal Algebraically angle ABC angle ACB angle BAC angle equal Apply Euc base BC chord circle ABC constr describe a circle diagonals diameter divided draw equal angles equiangular equilateral triangle equimultiples Euclid exterior angle Geometrical given circle given line given point given straight line gnomon greater hypotenuse inscribed intersection isosceles triangle less Let ABC line BC lines be drawn multiple opposite angles parallelogram parallelopiped pentagon perpendicular plane polygon produced Prop proportionals proved Q.E.D. PROPOSITION quadrilateral quadrilateral figure radius ratio rectangle contained rectilineal figure remaining angle right angles right-angled triangle segment semicircle shew shewn similar similar triangles solid angle square on AC tangent THEOREM touch the circle triangle ABC twice the rectangle vertex vertical angle wherefore
Popular passages
Page 93 - If a straight line be bisected and produced to any point, the square on the whole line thus produced, and the square on the part of it produced, are together double of the square on half the line bisected, and of the square on the line made up of the half and the part produced. Let the straight line AB be bisected in C, and produced to D ; The squares on AD and DB shall be together double of the squares on AC and CD. CONSTRUCTION. — From the point C draw CE at right angles to AB, and make it equal...
Page 118 - Guido, with a burnt stick in his hand, demonstrating on the smooth paving-stones of the path, that the square on the hypotenuse of a right-angled triangle is equal to the sum of the squares on the other two sides.
Page 145 - If a straight line touch a circle, and from the point of contact a straight line be drawn cutting the circle ; the angles which this line makes with the line touching the circle, shall be equal to the angles which are in the alternate segments of the circle.
Page 88 - If a straight line be divided into two equal parts and also into two unequal parts, the rectangle contained by the unequal parts, together with the square on the line between the points of section, is equal to the square on half the line.
Page 26 - ... upon the same side together equal to two right angles, the two straight lines shall be parallel to one another.
Page 36 - To a given straight line to apply a parallelogram, which shall be equal to a given triangle, and have one of its angles equal to a given rectilineal angle.
Page 144 - The angle in a semicircle is a right angle ; the angle in a segment greater than a semicircle is less than a right angle ; and the angle in a segment less than a semicircle is greater than a right angle.
Page 92 - If a straight line be divided into two equal, and also into two unequal parts, the squares on the two unequal parts are together double of the square on half the line and of the square on the line between the points of section. Let the straight line AB be divided into two equal parts...
Page xv - In every triangle, the square of the side subtending either of the acute angles is less than the squares of the sides containing that angle, by twice the rectangle contained by either of these sides, and the straight line intercepted between the perpendicular let fall upon it from the opposite angle, and the acute angle.
Page 67 - A proposition affirming the possibility of finding such conditions as will render a certain problem indeterminate or capable of innumerable solutions.