Elements of Geometry: Being Chiefly a Selection from Playfair's Geometry |
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Page 19
... angle . 31. An obtuse angled triangle is that which has an obtuse angle . 32. An acute angled triangle is ... angles right angles , but has not all its sides equal . 35. A parallelogram is that which has its two opposite GEOMETRY . 19 BOOK I.
... angle . 31. An obtuse angled triangle is that which has an obtuse angle . 32. An acute angled triangle is ... angles right angles , but has not all its sides equal . 35. A parallelogram is that which has its two opposite GEOMETRY . 19 BOOK I.
Page 20
... opposite sides parallel . 36. A trapezium is a four - sided figure , of which the opposite sides are not parallel ; and the diagonal is the straight line joining two of its opposite angles . ED . 37. A straight line joining two opposite ...
... opposite sides parallel . 36. A trapezium is a four - sided figure , of which the opposite sides are not parallel ; and the diagonal is the straight line joining two of its opposite angles . ED . 37. A straight line joining two opposite ...
Page 24
... angles to which the equal sides are opposite will be equal , each to each . * Let ABC , DEF be two triangles , which have the side AB equal to DE , and AC to DF ; and the angle A equal to D ; then the base BC will be equal to EF , and ...
... angles to which the equal sides are opposite will be equal , each to each . * Let ABC , DEF be two triangles , which have the side AB equal to DE , and AC to DF ; and the angle A equal to D ; then the base BC will be equal to EF , and ...
Page 25
... angles of one triangle equal to two angles of the other , each to each , and have also the sides between those ... opposite to them are equal . " For suppose the two angles at the base of each triangle to be- come equal to each other ...
... angles of one triangle equal to two angles of the other , each to each , and have also the sides between those ... opposite to them are equal . " For suppose the two angles at the base of each triangle to be- come equal to each other ...
Page 34
... angles , by Cor . 1 ; therefore all the angles made A at the point of concourse of the lines on both sides of AB are ... opposite angles will be equal . C Let the two straight lines AB , CD cut each other in the point E ; the angle AEC ...
... angles , by Cor . 1 ; therefore all the angles made A at the point of concourse of the lines on both sides of AB are ... opposite angles will be equal . C Let the two straight lines AB , CD cut each other in the point E ; the angle AEC ...
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Elements of Geometry: Being Chiefly a Selection From Playfair's Geometry John Playfair No preview available - 2023 |
Elements of Geometry: Being Chiefly a Selection From Playfair's Geometry John Playfair No preview available - 2023 |
Common terms and phrases
ABC is equal ABCD alternate angles angle ABC angle ACB angle BAC angles AGH angles equal base ABC bases and altitudes bisect centre chord circumference cone Consequently cylinder demonstrations described diagonals diameter divided draw equal angles equal arches equal bases equal circles equal to AC equiangular Euclid's Euclid's Elements exterior angle fore four quantities four right angles geometry given point given straight line gles greater Hence homologous sides intersect KLMN Let ABC meet opposite angles opposite side paral parallel lines parallel to CD parallelogram parallelopipeds perp perpendicular plane polygon prism Prop pyramid Q. E. D. COR Q. E. D. PROPOSITION radius rectangle contained right angled triangle Scholium segments semicircle side AC similar similar triangles solid square straight line &c subtended tangent THEOREM triangle ABC vertex wherefore
Popular passages
Page 36 - Any two sides of a triangle are together greater than the third side.
Page 80 - If a straight line be divided into any two parts, the square of the whole line is equal to the squares of the two parts, together with twice the rectangle contained by the parts.
Page 42 - To draw a straight line through a given point parallel to a given straight line. Let A be the given point, and BC the given straight line...
Page 30 - To bisect a given finite straight line, that is, to divide it into two equal parts. Let AB be the given straight line : it is required to divide it intotwo equal parts.
Page 20 - LET it be granted that a straight line may be drawn from any one point to any other point.
Page 38 - Problem. At a given point in a given straight line to make a rectilineal angle equal to a given rectilineal angle.
Page 113 - Wherefore also the angle BAD is equal to the angle CAD : Therefore the angle BAC is cut into two equal angles by the straight line AD.
Page 24 - DE ; the point B shall coincide with the point E, because AB is equal to DE; and AB coinciding with DE, AC shall coincide...
Page 36 - The greater angle of every triangle is subtended by the greater side, or has the greater side opposite to it.