Elements of Geometry and Plane Trigonometry: With an Appendix, and Copious Notes and Illustrations |
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Page 33
... AB ( I , 22. cor . ) parallel to CD ; and , for the same reason , the angle CAD being equal to ACB , the side AD is parallel to BC . Cor . Hence the angles of a square or rectangle are all of them right angles ; for the opposite sides ...
... AB ( I , 22. cor . ) parallel to CD ; and , for the same reason , the angle CAD being equal to ACB , the side AD is parallel to BC . Cor . Hence the angles of a square or rectangle are all of them right angles ; for the opposite sides ...
Page 40
... AB , with- out producing that line . In AB take any point C , and on BC ( I. 1. cor . ) de- scribe an isosceles ... square . Let AB be the side of the square which it is required to construct . From the extremity B draw , by the last ...
... AB , with- out producing that line . In AB take any point C , and on BC ( I. 1. cor . ) de- scribe an isosceles ... square . Let AB be the side of the square which it is required to construct . From the extremity B draw , by the last ...
Page 41
... square required . D B For , by this construction , the figure has all its sides e- qual , and one of its angles ABC a ... AB , draw a straight line AC , in which take the portion AD , and repeat it five times from A to C , join CB , and ...
... square required . D B For , by this construction , the figure has all its sides e- qual , and one of its angles ABC a ... AB , draw a straight line AC , in which take the portion AD , and repeat it five times from A to C , join CB , and ...
Page 52
... squares of the sides AB and BC . For produce DA to K , and through B draw MBL pa- rallel to DA ( I. 23. ) and ... AB , are equal ( 1. 20. ) , and consequently the side AC is equal to AK . Hence the rectangle or rhomboid AM is equivalent ...
... squares of the sides AB and BC . For produce DA to K , and through B draw MBL pa- rallel to DA ( I. 23. ) and ... AB , are equal ( 1. 20. ) , and consequently the side AC is equal to AK . Hence the rectangle or rhomboid AM is equivalent ...
Page 53
... square of BC . Consequently the whole square , ADEC , of the hypotenuse , contains the same space as both together of the squares described on the two sides AB and BC . Cor . Hence the square of a side AB is equivalent to the rectangle ...
... square of BC . Consequently the whole square , ADEC , of the hypotenuse , contains the same space as both together of the squares described on the two sides AB and BC . Cor . Hence the square of a side AB is equivalent to the rectangle ...
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Common terms and phrases
ABCD adjacent angle altitude angle ABC angle ADB angle BAC base AC bisect centre chord circle circumference consequently construction contained angle cosine decagon denote describe diameter difference distance diverging lines divided draw equal to BC equilateral triangle equivalent to twice evidently exterior angle given greater half Hence hypotenuse inscribed isosceles triangle join let fall likewise measure parallel perpendicular point G polygon PROB PROP Proposition quadrilateral figure quantities radius ratio rectangle rectangle contained rectilineal figure rhomboid right angles right-angled triangle Scholium segments semicircle semiperimeter side AC sides AB sine square of AC squares of AB straight line tangent THEOR tion triangle ABC twice the rectangle twice the square vertex vertical angle whence Wherefore
Popular passages
Page 30 - ... if a straight line, &c. QED PROPOSITION 29. — Theorem. If a straight line fall upon two 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 likewise the two interior angles upon the same side together equal to two right angles.
Page 333 - The first of four magnitudes is said to have the same ratio to the second which the third has to the fourth, when any...
Page 294 - If a straight line meets two straight lines, so as to " make the two interior angles on the same side of it taken " together less than two right angles...
Page 10 - A diameter of a circle is a straight line drawn through the centre, and terminated both ways by the circumference.
Page 137 - Componendo, by composition ; when there are four proportionals, and it is inferred that the first together with the second, is to the second, as the third together with the fourth, is to the fourth.
Page 84 - The angle at the centre of a circle is double of the angle at the circumference upon the same base, that is, upon the same part of the circumference.
Page 292 - Thus, for" example, he to whom the geometrical proposition, that the angles of a triangle are together equal to two right angles...
Page 93 - UPON a given straight line to describe a segment of a circle containing an angle equal to a given rectilineal angle.
Page 38 - 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 58 - The rectangle contained by the sum and difference of two straight lines is equivalent to the difference of the squares of these lines.