## A companion to Euclid: being a help to the understanding and remembering of the first four books. With a set of improved figures, and an original demonstration of the proposition called in Euclid the twelfth axiom, by a graduate |

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Resultat 1-5 av 6

Side 7

The Golden Rule for the learner of Geometry is never to

proposition , till he thoroughly understands the preceding one . For in this science

the higher steps so completely depend on the lower ones , that it is next to

impossible ...

The Golden Rule for the learner of Geometry is never to

**pass**on to a newproposition , till he thoroughly understands the preceding one . For in this science

the higher steps so completely depend on the lower ones , that it is next to

impossible ...

Side 51

If in a circle 10 straight lines cut one another , which do not both

centre , they do not bisect each other . Steps of the Demonstration . Suppose that

AC , BD do bisect each other in E . ( State that this is evidently impossible if one ...

If in a circle 10 straight lines cut one another , which do not both

**pass**through thecentre , they do not bisect each other . Steps of the Demonstration . Suppose that

AC , BD do bisect each other in E . ( State that this is evidently impossible if one ...

Side 54

Then suppose that from point F to the another line Fk besides fh can be drawn =

Fg , and prove , on that supposition , 2 . that FK = Fh ; i . e . a line near to = one

more remote from that

Then suppose that from point F to the another line Fk besides fh can be drawn =

Fg , and prove , on that supposition , 2 . that FK = Fh ; i . e . a line near to = one

more remote from that

**passing**through the centre , which is impossible by the ... Side 58

If two circles touch each other externally , the straight line B which joins their

centres shall

the line joining the centres

that ...

If two circles touch each other externally , the straight line B which joins their

centres shall

**pass**through the point of contact . Prove that the supposition , thatthe line joining the centres

**passes**otherwise than through a is false , by showingthat ...

Side 68

a o described with centre d and one of these lines as distance , will

the extremities of the other two . oi Steps of the Demonstration to Case 2nd , In

which _ ABD + _ BAD . 1 . Prove that AE = EB , that ( in AS ADE , CDE ) base AE

...

a o described with centre d and one of these lines as distance , will

**pass**throughthe extremities of the other two . oi Steps of the Demonstration to Case 2nd , In

which _ ABD + _ BAD . 1 . Prove that AE = EB , that ( in AS ADE , CDE ) base AE

...

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alternate angle contained angle equal applied Argument ad absurdum base bisect BOOK centre circumference coincides construction Demonstration described diameter directed divided draw drawn Edition Engravings equal equiangular equilateral Euclid extremities fall figure given circle given point given rectilineal given straight line greater HISTORY impossible inscribe interior joins learner least less meet Nature necessary opposite parallel parallelogram pass pentagon point of contact Problem produced proof PROPOSITION PROPOSITION VIII PROPOSITION XV Proved by showing READINGS rectangle contained right angles right line right Zs segment shows the supposition sides similarly square Steps straight line Suppose supposition is false Theorem touch triangle VOLUME whole whole line YOUNG

### Populære avsnitt

Side 24 - 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, namely, either t}le sides adjacent to the equal...

Side 45 - To divide a given straight line 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.

Side 18 - If, at a point in a straight line, two other straight lines, upon the opposite sides of it, make the adjacent angles together equal to two right angles, these two straight lines shall be in one and the same straight line.

Side 61 - From this it is manifest that the straight line which is drawn at right angles to the diameter of a circle from the extremity of it, touches the circle...

Side 37 - In any right-angled triangle, the square which is described upon the side subtending the right angle, is equal to the squares described upon the sides which contain the right angle.

Side 76 - IF from any point without a circle two straight lines be drawn, one of which cuts the circle, and the other touches it ; the rectangle contained by the whole line which cuts the circle, and the part of it without the circle, shall be equal to the square of the line which touches it.

Side 77 - If from a point without a circle there be drawn two straight lines, one of which cuts the circle, and the other meets it, and if the rectangle contained by the whole line which cuts the circle, and the part of it without the circle, be equal to the square on GEOMETRY.

Side 72 - If a straight line touch a circle, and from the point of contact a straight line be drawn at right angles to the touching line, the centre of the circle shall be in that line.

Side 27 - If a straight line fall on two parallel straight lines, it makes the alternate angles equal to one another, and the exterior angle equal to the interior and opposite angle on the same side; and also the two interior angles on the same side together equal to two right angles.