## The First Six Books: Together with the Eleventh and Twelfth |

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Page 10

... ftraight line ' ftanding on ano- ther ftraight line makes the adjacent angles equal to one another , each of the angles is called a right angle ; and the ftraight line which stands on the other is called a

... ftraight line ' ftanding on ano- ther ftraight line makes the adjacent angles equal to one another , each of the angles is called a right angle ; and the ftraight line which stands on the other is called a

**perpendicular**to it . XI . Page 23

It is required to draw a straight line

It is required to draw a straight line

**perpendicular**to AB from the point C. Take any point D upon the other fide of AB , and from the centre C , at the distance CD , defcribe the circle EGF C a Book I. 10. Def . 1 . E H b 3. Page 63

IN obtufe angled triangles , if a

IN obtufe angled triangles , if a

**perpendicular**be drawn from any of the acute angles to the oppofite fide pro- duced , the fquare of the fide fubtending the obtuse angle is greater than the fquares of the fides containing the ob- tufe ... Page 64

THEOR . the of the fide any of the acute angles , is lefs than the fquares of the fides containing that angle , by twice the rectangle contained by either of these fides , and the ftraight line intercepted . between the

THEOR . the of the fide any of the acute angles , is lefs than the fquares of the fides containing that angle , by twice the rectangle contained by either of these fides , and the ftraight line intercepted . between the

**perpendicular**... Page 65

Laftly , Let the fide AC be

Laftly , Let the fide AC be

**perpendicular**to BC ; then is BC the ftraight line between the**perpendicular**and the acute angle at B ; and it is manifeft that the fquares of AB , BC are e- qual to the fquare of AC , and twice the fquare of ...### What people are saying - Write a review

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### Common terms and phrases

added alfo alſo altitude angle ABC angle BAC bafe baſe becauſe bifected Book Book XI centre circle circle ABCD circumference common cone cylinder defcribed definition demonftrated diameter divided double draw drawn equal equal angles equiangular equimultiples excefs fame fame multiple fecond fegment fhall fides fimilar firft folid folid angle fore four fourth fquare fquare of AC ftraight line given angle given in fpecies given in pofition given magnitude given ratio greater Greek half join lefs magnitude meet oppofite parallel parallelogram perpendicular plane prifms produced PROP propofition proportionals pyramid rectangle rectangle contained remaining right angles Take taken thefe THEOR theſe third triangle ABC wherefore whole

### Popular passages

Page 474 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees ; and each degree into 60 equal parts, called minutes ; and each minute into 60 equal parts, called seconds ; and these into thirds, &c.

Page 170 - 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 81 - THE straight line drawn at right angles to the diameter of a circle, from the extremity of...

Page 105 - DEF are likewise equal (13. i.) to two right angles ; therefore the angles AKB, AMB are equal to the angles DEG, DEF, of which AKB is equal to DEG ; wherefore the remaining angle AMB is equal to the remaining angle DEF.

Page 167 - AC the same multiple of AD, that AB is of the part which is to be cut off from it : join BC, and draw DE parallel to it : then AE is the part required to be cut off.

Page 10 - When a straight line standing on another straight line makes the adjacent angles equal to one another, each of the angles is called a right angle; and the straight line which stands on the other is called a perpendicular to it.

Page 62 - 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 112 - To describe an equilateral and equiangular pentagon about a given circle. • Let ABCDE be the given circle; it is required to describe an equilateral and equiangular pentagon about the circle ABCDE. Let the angles of a pentagon, inscribed in the circle...

Page 200 - 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 38 - 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.