## The Elements of Euclid: With Many Additional Propositions, & Explanatory Notes, Etc, Part 1 |

### From inside the book

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Page viii

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**termed**the subject ; 2nd , the sign of affirmation or denial , called the copula ; and 3rd , the property , quality , or circumstance asserted , named the predicate . For ex- ample , the assertion that " the sun is round " is a ... Page xv

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**termed**conversion per accidens , namely , by diminish- ing its quantity ( its quality remaining unaltered ) so that ... (**termed**the conclusion ) is manifestly established , by ad- mitting the truth of the two first (**termed**the premises ) ... Page xvi

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**termed**) , may be formed with the same terms ; thus , the major pre- miss may be either A , E , I , or O , and each of these may have any one again for its minor premiss , which gives 16 varieties , and each of these again may have any ... Page xviii

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**termed**perfect , and the other figures which require to be reduced to the first before they can be com- pared with the dictum are**termed**imperfect . The reduction of a syllogism is either ostensive or ad impossibile . Ostensive ... Page xix

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**termed**the reductio ad absurdum , and is very frequently employed by Euclid , particularly in the demonstration of propositions from their converse . By examining the names given to the modes , it will be observed that their initial ...### Other editions - View all

### Common terms and phrases

AC and CB AC is equal angle ABC angle BCD angle equal area to double area to twice bisect chord circle ABC circumference Constr CONSTRUCTION COROLLARY DB is equal DEMONSTRATION diagonal divided double the rectangle draw equal angles equal in area equal to AC equilateral Euclid external angle Find the center finite straight line Geometry given angle given line greater Hypoth HYPOTHESES intersect join less line BC lines be drawn magnitude major premiss opposite sides parallel parallelogram perpendicular predicate premises produced proposition quadratic equation reductio ad absurdum right angles SCHOLIA SCHOLIUM second power segment sides AC square on AC square on half squares on AB syllogism termed THEOREM THEOREM.-If triangle ABC twice the rectangle twice the square vertex whole line

### Popular passages

Page 24 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.

Page 114 - In obtuse-angled triangles, if a perpendicular be drawn from either of the acute angles to the opposite side produced, the square on the side subtending the obtuse angle is greater than the squares on the sides containing the obtuse angle, by twice the rectangle contained by the side...

Page xiv - A circle is a plane figure contained by one line, which is called the circumference, and is such, that all straight lines drawn from a certain point within the figure to the circumference are equal to one another : 16. And this point is called the centre of the circle.

Page 13 - The difference between any two sides of a triangle is less than the third side.

Page 111 - AFC. (in. 21.) Hence in the triangles ADE, AFC, there are two angles in the one respectively equal to two angles in the other, consequently, the third angle CAF is equal to the third angle DAB ; therefore the arc DB is equal to the arc CF, (in.

Page 89 - ... the centre of the circle shall be in that line. Let the straight line DE touch the circle ABC in C, and from C let CA be drawn at right angles to DE ; the centre of the circle is in CA.

Page 70 - EQUAL circles are those of which the diameters are equal, or from the centres of which the straight lines to the circumferences are equal. ' This is not a definition, but a theorem, the truth of ' which is evident; for, if the circles be applied to one ' another, so that their centres coincide, the circles ' must likewise coincide, since the straight lines from

Page 34 - To describe a parallelogram equal to a given rectilineal figure, and having an angle equal to a given rectilineal angle.

Page 22 - If a straight line meet two straight lines, so as to make the two interior angles on the same side of it taken together less than two right angles...