## The Elements of Euclid: The Errors, by which Theon, Or Others, Have Long Ago Vitiated These Books, are Corrected, and Some of Euclid's Demonstrations are Restored. Also, The Book of Euclid's Data, in Like Manner Corrected. viz. the first six books, together with the eleventh and twelfthMathew Carey, and sold by J. Conrad & Company, S. F. Bradford, Birch & Small, and Samuel Etheridge. Printed by T. & G. Palmer, 116, High-Street., 1806 - 518 pages |

### From inside the book

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... nor any geometer be-

... nor any geometer be-

**fore**Theon's time , ever made use of , and of which there is * not to be found the least appearance in any of their writings ; and , as this definition did much embarrass beginners , Hist . of sci . PREFACE. ... Page 20

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**fore**, because AC is equal to AD in the triangle ACD , the angles ECD , FDC upon the other side of the base CD are equal a to one another , but the angle ECD is greater than the angle BCD ; wherefore the angle FDC is likewise greater ... Page 30

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**fore**FK is equal to A : again , because G is the centre of the ˆ 15. Def . circle LKH , GH is equal to GK ; but GH is equal to C ; therefore also GK is equal to C ; and FG is equal to B ; there-**fore**the three straight lines KF , FG ... Page 33

... con- tain equal angles ; wherefore the base AC is equal to the base DF , and the third angle BAC to the third angle EDF . There-

... con- tain equal angles ; wherefore the base AC is equal to the base DF , and the third angle BAC to the third angle EDF . There-

**fore**, if two triangles , & c . Q. E. D. E Book I. } PROP . XXVII . THEOR . IF OF EUCLID . 33. Page 36

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**fore**also AGK is equal to GKD ; and they are alternate angles ; b 27. 1. therefore AB is parallel b to CD . Wherefore , straight lines , & c . Q. E. D. PROP . XXXI . PROâ . TO draw a straight line through a given point pa- rallel to a ...### Other editions - View all

### Common terms and phrases

altitude angle ABC angle BAC base BC BC is equal BC is given bisected Book XI centre circle ABCD circumference cone cylinder demonstrated described diameter draw drawn equal angles equiangular equimultiples Euclid excess fore given angle given in magnitude given in position given in species given magnitude given point given ratio given straight line gnomon greater join less Let ABC meet multiple opposite parallel parallelogram parallelogram AC perpendicular point F polygon prism proposition pyramid Q. E. D. PROP radius rectangle CB rectangle contained rectilineal figure remaining angle right angles segment sides BA similar solid angle solid parallelepipeds square of AC straight line AB straight line BC tangent THEOR third triangle ABC triplicate ratio vertex wherefore

### Popular passages

Page 28 - Any two sides of a triangle are together greater than the third side.

Page 62 - 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.

Page 28 - IF, from the ends of the 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. Let...

Page 57 - PROP. VIII. THEOR. IF a straight line be divided into any two parts, tour times the rectangle contained by the whole line, and one of the parts, together with the square of the other part, is equal to the square of the straight line which is made up of the whole and that part.

Page 26 - If one side of a triangle be produced, the exterior angle is greater than either of the interior opposite angles.

Page 163 - 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 17 - THE angles at the base of an isosceles triangle are equal to one another : and, if the equal sides be produced, the angles upon the other side of the base shall be equal.

Page 189 - In right angled triangles, the rectilineal figure described upon the side opposite to the right angle, is equal to the similar, and similarly described figures upon the sides containing the right angle.

Page 37 - 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 sidef. 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 178 - Therefore, universally, similar rectilineal figures are to one another in the duplicate ratio of their homologous sides.