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 6
... interior angles on the same side of it taken together less than two right angles ; these straight lines being continually produced , shall at length meet upon that side on which are the angles which are less than two right angles ...
... interior angles on the same side of it taken together less than two right angles ; these straight lines being continually produced , shall at length meet upon that side on which are the angles which are less than two right angles ...
Page 17
... interior opposite angles . Let ABC be a triangle , and let the side BC be produced to D. Then the exterior angle ACD shall be greater than either of the interior opposite angles CBA or BAC . A F B E G Bisect AC in E , ( 1. 10. ) and ...
... interior opposite angles . Let ABC be a triangle , and let the side BC be produced to D. Then the exterior angle ACD shall be greater than either of the interior opposite angles CBA or BAC . A F B E G Bisect AC in E , ( 1. 10. ) and ...
Page 18
... interior and opposite angle ABC ; ( 1. 16. ) to each of these unequals add the angle ACB ; therefore the angles ACD , ACB are greater than the angles ABC , ACB ; but the angles ACD , ACB are equal to two right angles ; ( I. 13 ...
... interior and opposite angle ABC ; ( 1. 16. ) to each of these unequals add the angle ACB ; therefore the angles ACD , ACB are greater than the angles ABC , ACB ; but the angles ACD , ACB are equal to two right angles ; ( I. 13 ...
Page 19
... interior and opposite angle DCB ; ( I. 16. ) but the angle ADB has been proved equal to the angle ABD , therefore the angle ABD is greater than the angle DCB ; wherefore much more is the angle ABC greater than the angle ACP . Therefore ...
... interior and opposite angle DCB ; ( I. 16. ) but the angle ADB has been proved equal to the angle ABD , therefore the angle ABD is greater than the angle DCB ; wherefore much more is the angle ABC greater than the angle ACP . Therefore ...
Page 21
... interior and opposite angle ; ( 1. 16. ) therefore the exterior angle BDC of the triangle CDE is graeter than the interior and opposite angle CED ; for the same reason , the exterior angle CED of the triangle ABE is greater than the ...
... interior and opposite angle ; ( 1. 16. ) therefore the exterior angle BDC of the triangle CDE is graeter than the interior and opposite angle CED ; for the same reason , the exterior angle CED of the triangle ABE is greater than 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.