The First Six Books of the Elements of Euclid: With Notes |
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Page 3
... opposite sides are parallel . 31. A square is a quadrilateral figure , which has all its sides equal , and all its angles right angles . 32. Rectilineal figures , which have more than four sides , are called polygons . POSTULATES . Let ...
... opposite sides are parallel . 31. A square is a quadrilateral figure , which has all its sides equal , and all its angles right angles . 32. Rectilineal figures , which have more than four sides , are called polygons . POSTULATES . Let ...
Page 5
... opposite to the equal sides , are equal ( E to A and F to C ) ; and also the triangles themselves . For if the triangle EDF be so applied to the trian- gle ABC , that the point D may be on B , and the side DE on BA , and that DF and BC ...
... opposite to the equal sides , are equal ( E to A and F to C ) ; and also the triangles themselves . For if the triangle EDF be so applied to the trian- gle ABC , that the point D may be on B , and the side DE on BA , and that DF and BC ...
Page 6
... equilateral triangle is also equian- gular ; for whatever side is taken for the base , the an- gles adjacent to it are equal , since they are opposite to equal sides . PROP . VI . THEOR . If two angles ( 6 ELEMENTS OF EUCLID ,
... equilateral triangle is also equian- gular ; for whatever side is taken for the base , the an- gles adjacent to it are equal , since they are opposite to equal sides . PROP . VI . THEOR . If two angles ( 6 ELEMENTS OF EUCLID ,
Page 7
... opposite to them ( AC and AB ) are also equal . If the sides be not equal , let one of them AB be greater than the other , and from it cut off DB equal to AC ( 1 ) , and join CD . 1 . ( 1 ) Prop . 3 . Then in the triangles DBC , and ACB ...
... opposite to them ( AC and AB ) are also equal . If the sides be not equal , let one of them AB be greater than the other , and from it cut off DB equal to AC ( 1 ) , and join CD . 1 . ( 1 ) Prop . 3 . Then in the triangles DBC , and ACB ...
Page 8
... ( 3 ) . Schol . It is evident that the remaining angles A and E , C and D , opposite to the equal sides , are equal and also that the triangles themselves are equal . PROP . IX . PROB . To bisect a given ELEMENTS OF EUCLID ,
... ( 3 ) . Schol . It is evident that the remaining angles A and E , C and D , opposite to the equal sides , are equal and also that the triangles themselves are equal . PROP . IX . PROB . To bisect a given ELEMENTS OF EUCLID ,
Common terms and phrases
absurd AC and BD AC and CB AC is equal angle ABC angle ACD angle BAC angle equal base bisected centre circumference Constr constructed contained in CD demonstrated described double the rectangle double the square drawn equal angles equal to AC equal to double equi equi-multiples equi-submultiples equiangular Euclid evident external angle fore form one right four magnitudes proportional four right angles fourth given angle given circle given line given right line given triangle gles half a right Hypoth inscribed less line CD manner multiple oftener opposite parallel parallelogram perpendicular PROB produced Prop proposition radius rectangle under AC right angles right line AB Schol segment side AC sides AB similar squares of AC submultiple taken tangent THEOR third tiple triangle ABC vertex
Popular passages
Page 147 - A plane rectilineal angle is the inclination of two straight lines to one another, which meet together, but are not in the same straight line.
Page 3 - Things which are equal to the same thing are equal to one another. 2. If equals be added to equals, the wholes are equal. 3. If equals be taken from equals, the remainders are equal. 4. If equals be added to unequals, the wholes are unequal. 5. If equals be taken from unequals, the remainders are unequal. 6. Things which are double of the same are equal to one another.
Page 22 - 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 16 - If two triangles have two sides of the one respectively equal to two sides of the other, and the contained angles supplemental, the two triangles are equal.
Page 148 - A plane angle is the inclination of two lines to one another in a plane, which meet together, but are not in the same direction.
Page 2 - A diameter of a circle is a straight line drawn through the centre, and terminated both ways by the circumference.
Page 92 - F) a ratio compounded of the ratios which the first has to the second, the second to the third, the third to the fourth (A to D, D to C, and C to F) ; and so on to the last.
Page 93 - AXIOMS. 1. Equimultiples of the same, or of equal magnitudes, are equal to one another. 2. Those magnitudes, of which the same or equal magnitudes are equimultiples, are equal to one another. 3. A multiple of a greater magnitude is greater than the same multiple of a less. 4. That magnitude, of which a multiple is greater than the same multiple of another, is greater than that other magnitude.
Page 25 - DE : but equal triangles on the same base and on the same side of it, are between the same parallels ; (i.
Page 2 - 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.