Elements of Geometry: Containing the First Six Books of Euclid, with a Supplement of the Quadrature of the Circle and the Geometry of Solids |
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Page 8
... fore CA , AB , BC are equal to one another ; and the triangle ABC is therefore equilateral , and it is described upon the given straight line AB . Which was required to be done . om . PROP . II . PROB . FROM a given point to draw a ...
... fore CA , AB , BC are equal to one another ; and the triangle ABC is therefore equilateral , and it is described upon the given straight line AB . Which was required to be done . om . PROP . II . PROB . FROM a given point to draw a ...
Page 12
... fore , because in the triangles DBC , ACB , DB is equal to AC , and BC common to both , the two sides DB , BC are equal to the two AC , CB , each to each ; but the angle DBC is also equal to the angle ACB ; therefore the base DC is ...
... fore , because in the triangles DBC , ACB , DB is equal to AC , and BC common to both , the two sides DB , BC are equal to the two AC , CB , each to each ; but the angle DBC is also equal to the angle ACB ; therefore the base DC is ...
Page 15
... fore the angle DAF is equal to the angle EAF ; wherefore the given rectilineal angle BAC is bisected by B D the straight line AF . Which was to be done . PROP . X. PROB . A E b 1. 1 . c 8. 1 . F TO bisect a given finite straight line ...
... fore the angle DAF is equal to the angle EAF ; wherefore the given rectilineal angle BAC is bisected by B D the straight line AF . Which was to be done . PROP . X. PROB . A E b 1. 1 . c 8. 1 . F TO bisect a given finite straight line ...
Page 19
... fore the angles CBA , ABE are equal to the angles CBA , ABD : take away the common angle ABC , and the remaining angle ABE is equal to the remaining angle ABD , the less b 3. Ax . to the greater , which is impossible ; therefore BE is ...
... fore the angles CBA , ABE are equal to the angles CBA , ABD : take away the common angle ABC , and the remaining angle ABE is equal to the remaining angle ABD , the less b 3. Ax . to the greater , which is impossible ; therefore BE is ...
Page 22
... is equal to AC , the angle ADC is like- wise equal to ACD ; but the angle BCD is greater than the angle ACD ; there- B C fore the angle BCD is greater than the angle ADC ; and be- Book I. cause the angle BCD of the triangle DCB 22 ELEMENTS.
... is equal to AC , the angle ADC is like- wise equal to ACD ; but the angle BCD is greater than the angle ACD ; there- B C fore the angle BCD is greater than the angle ADC ; and be- Book I. cause the angle BCD of the triangle DCB 22 ELEMENTS.
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Common terms and phrases
ABC is equal ABCD altitude angle ABC angle ACB angle BAC angle contained angle EDF arch base BC bisected Book centre circle ABC circumference coincide cylinder definition demonstrated diameter draw drawa equal angles equiangular equilateral polygon equimultiples Euclid exterior angle fore four right angles given circle given straight line greater inscribed interior and opposite join less Let ABC Let the straight meet multiple opposite angle parallelogram perpendicular point F polygon prism PROB produced proportional proposition pyramid Q. E. D. COR Q. E. D. PROP ratio rectangle contained rectilineal figure remaining angle segment solid angle solid parallelepipeds straight line AB straight line AC Suppl THEOR third touches the circle triangle ABC triangle DEF
Popular passages
Page 121 - 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 42 - TO a given straight line to apply a parallelogram, which shall be equal to a given triangle, and have one of its angles equal to a given rectilineal angle.
Page 63 - Therefore, in obtuse-angled triangles, &c. QED PROP. XIII. THEOREM. In every triangle, the square of the side subtending either of the acute angles is less than the squares of the sides containing that angle, by twice the rectangle contained by either of these sides, and the straight line intercepted between the perpendicular let fall upon it from the opposite angle, and the acute angle.
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 183 - Equiangular parallelograms have to one another the ratio which is compounded of the ratios of their sides. Let AC, CF be equiangular parallelograms having the angle BCD equal to the angle ECG ; the ratio of the parallelogram AC to the parallelogram CF is the same with the ratio which is compounded •f the ratios of their sides.
Page 3 - A diameter of a circle is a straight line drawn through the centre, and terminated both ways by the circumference.
Page 291 - 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 160 - ... extremities of the base shall have the same ratio which the other sides of the triangle have to one...
Page 10 - ... shall be greater than the base of the other. Let ABC, DEF be two triangles, which have the two sides AB, AC, equal to the two DE, DF, each to each, viz.
Page 14 - Therefore, upon the same base, and on the same side of it, there cannot be two triangles that have their sides which are terminated in one extremity of the base equal to one another, and likewise those which are terminated in the other extretnity equal to one another.