## The Elements of Euclid, the parts read in the University of Cambridge [book 1-6 and parts of book 11,12] with geometrical problems, by J.W. Colenso1846 |

### From inside the book

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... for greater or less read less or greater . N.B. In the PROBLEMS , the name trapezium will be restricted to a quadrilateral , two of whose opposite sides are

... for greater or less read less or greater . N.B. In the PROBLEMS , the name trapezium will be restricted to a quadrilateral , two of whose opposite sides are

**parallel**. 1 THE ELEMENTS OF EUCLID . BOOK I. DEFINITIONS . Page 4

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**Parallel**straight lines are such as are in the same plane , and , being produced ever so far both ways , do not meet . POSTULATES . Let it be granted , 1. That a straight line may be drawn from any one point to any other point : 11 ... Page 28

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**parallel**. Let the straight line EF , which falls upon the two straight lines AB , CD , make the alternate angles AEF , EFD , equal to one another : AB is**parallel**to CD . For , if it be not**parallel**, AB and CD being produced shall ... Page 29

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**parallel**to one another : Therefore AB is**parallel**to CD . Wherefore , If a straight line & c . Q. E. D. PROP . XXVIII . THEOR . If a straight line , falling upon two other straight lines , makes the exterior angle equal to the interior ... Page 30

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**parallel**straight lines , it makes the alternate angles equal to one another , and the exterior angle equal to the interior and opposite upon the same side , and also the two interior angles upon the same side together equal to two ...### Other editions - View all

The Elements of Euclid, the Parts Read in the University of Cambridge [Book ... Euclides No preview available - 2016 |

### Common terms and phrases

ABCD angle ABC angle ACB angle BAC base base BC BC is equal bisected centre chord circle circle ABC circumference common described diameter difference divided double draw drawn equal angles equiangular equimultiples extremities fall figure fore four fourth given circle given line given point given straight line greater half inscribed intersection join less Let ABC lines be drawn lines drawn magnitudes manner meet multiple opposite sides parallel parallelogram pass perpendicular plane polygon PROB produced PROP proportionals Q.E.D. PROP ratio rectangle rectangle contained rectilineal figure right angles segment semicircle shew shewn sides similar square square of AC Take taken THEOR third touches the circle triangle ABC Wherefore whole

### Popular passages

Page 42 - 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 4 - Let it be granted that a straight line may be drawn from any one point to any other point.

Page 33 - F, which is the common vertex of the triangles: that is », together with four right angles. 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.

Page 62 - 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 of the line between the points of section, is equal to the square of half the line.

Page 22 - If from the ends of a side of a triangle, there be drawn two straight lines to a point within the triangle, these shall be less than the other two sides of the triangle, but shall contain a greater angle.

Page 58 - If there be two straight lines, one of which is divided into any number of parts, the rectangle contained by the two straight lines is equal to the rectangles contained by the undivided line, and the several parts of the divided line.

Page 146 - ... may be demonstrated from what has been said of the pentagon : and likewise a circle may be inscribed in a given equilateral and equiangular hexagon, and circumscribed about it, by a method like to that used for the pentagon.

Page 194 - If two triangles have one angle of the one equal to one angle of the other and the sides about these equal angles proportional, the triangles are similar.

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 : 16.

Page 69 - To divide a given straight line into two parts, so that the rectangle contained by the whole, and one of the parts, may be equal to the square of the other part.