## 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, to this Second Edition is Added the Book of Euclid's Data. In Like Manner Corrected. viz. the first six books, together with the eleventh and twelfth |

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Page 46

1. them , the exterior angle BGC is equal to the interior and opposite angle ADB ;

but ADB is equal d to the angle ABD , because BA is equal to AD , being sides of

a square ;

1. them , the exterior angle BGC is equal to the interior and opposite angle ADB ;

but ADB is equal d to the angle ABD , because BA is equal to AD , being sides of

a square ;

**wherefore**the angle CGB is equal to the angle GBC , and A с B C. 6. Page 63

gles in one equal to two angles in the other , and the side EF which Book III , is

oppofite to one of the equal angles in each , is common to both ; therefore the

other sides are equal " , AF therefore is equal to FB .

& c .

gles in one equal to two angles in the other , and the side EF which Book III , is

oppofite to one of the equal angles in each , is common to both ; therefore the

other sides are equal " , AF therefore is equal to FB .

**Wherefore**if a straight line ,& c .

Page 154

because the angle DEF is equal to the angle GEF , and GEF to the angle ABC ;

therefore the angle ABC is equal to the angle DEF . for the same reason , the

angle ...

**Wherefore**the angle DFE is equal to the angle GFE , and EDF to EGF . andbecause the angle DEF is equal to the angle GEF , and GEF to the angle ABC ;

therefore the angle ABC is equal to the angle DEF . for the same reason , the

angle ...

Page 155

At the points D , F , in the straight line DF , make the angle a . 23. 1 . FDG equal to

either of the angles BAC , EDF ; and the angle DFG equal to the angle ACB .

D G ...

At the points D , F , in the straight line DF , make the angle a . 23. 1 . FDG equal to

either of the angles BAC , EDF ; and the angle DFG equal to the angle ACB .

**wherefore**the remaining A angle at B is equal to the remaining one at Gb , andD G ...

Page 389

Dat . point F is given . and the points D , E are given ; therefore each of the

straight lines DE , EF , FD is given in magnitude .

triangle DEF is given in species d ; and it is similar to the tri- d 42. Dat . angle

ABC ; which ...

Dat . point F is given . and the points D , E are given ; therefore each of the

straight lines DE , EF , FD is given in magnitude .

**wherefore**c . 29. Dat . thetriangle DEF is given in species d ; and it is similar to the tri- d 42. Dat . angle

ABC ; which ...

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### Common terms and phrases

added alſo altitude angle ABC angle BAC baſe BC is given becauſe Book Book XI caſe circle circle ABCD circumference common cone cylinder Definition demonſtrated deſcribed diameter divided double draw drawn equal equal angles equiangular equimultiples exceſs fame fides firſt folid fore four fourth given angle given in poſition given in ſpecies given magnitude given ratio given ſtraight line greater Greek half join leſs likewiſe magnitude manner meet muſt oppoſite parallel parallelogram perpendicular plane priſm produced PROP proportionals Propoſition pyramid reaſon rectangle remaining right angles ſame ſecond ſegment ſhall ſhewn ſides ſimilar ſolid ſquare ſquare of AC taken THEOR theſe third thro triangle ABC wherefore whole

### Popular passages

Page 5 - Let it be granted that a straight line may be drawn from any one point to any other point.

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 48 - If a straight line be divided into any two parts, the squares of the whole line, and of one of the parts, are equal to twice the rectangle contained by the whole and that part, together with the square of the other part. Let the straight line AB be divided into any two parts in the point C; the squares of AB, BC are equal to twice the rectangle AB, BC, together with the square of AC.

Page 73 - The straight line drawn at right angles to the diameter of a circle, from the extremity of it, falls without the circle; and no straight line can be drawn from the extremity between that straight line and the circumference, so as not to cut the circle...

Page 105 - If two triangles have two angles of the one equal to two angles of the other, each to each, and one side equal to one side, viz. either the sides adjacent to the equal...

Page 3 - 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.

Page 167 - Similar triangles are to one another in the duplicate ratio of their homologous sides.

Page 54 - AB be the given straight line ; it is required to divide it into two parts, so that the rectangle contained by the whole, and one of the parts, shall be equal to the square of the other part.

Page 47 - 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 37 - To describe a parallelogram that shall be equal to a given triangle, and have one of its angles equal to a given rectilineal angle.