Elements of Geometry: Containing the First Six Books of Euclid with a Supplement on the Quadrature of the Circle, and the Geometry of Solids : to which are Added, Elements of Plane and Spherical Trigonometry |
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Page 8
... straight line . " " COR . Hence two straight lines cannot inclose a space . Neither can two straight lines have a common segment ; that is , they cannot coincide " in part , without coinciding altogether . " 66 4. A superficies is that ...
... straight line . " " COR . Hence two straight lines cannot inclose a space . Neither can two straight lines have a common segment ; that is , they cannot coincide " in part , without coinciding altogether . " 66 4. A superficies is that ...
Page 9
... 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 perpendicu- lar to it . 8. An ...
... 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 perpendicu- lar to it . 8. An ...
Page 11
... straight lines are such as are in the same plane , and which being produced ever so far both ways , do not meet . POSTULATES . 1. LET it be granted that a straight line ... straight line may be produced to any length in a straight line .. 3 ...
... straight lines are such as are in the same plane , and which being produced ever so far both ways , do not meet . POSTULATES . 1. LET it be granted that a straight line ... straight line may be produced to any length in a straight line .. 3 ...
Page 12
... straight line . Let AB be the given straight line ; it is required to describe an equi- lateral triangle upon it . From the centre A , at the dis- tance AB , describe ( 3. Postulate ) the circle BCD , and from the cen- tre B , at the ...
... straight line . Let AB be the given straight line ; it is required to describe an equi- lateral triangle upon it . From the centre A , at the dis- tance AB , describe ( 3. Postulate ) the circle BCD , and from the cen- tre B , at the ...
Page 13
... straight line AL is equal to BC . Wherefore , from the given point A , a straight line AL has been drawn equal to the given straight line BC . PROP . III . PROB . From the greater of two given straight lines to cut off a part equal to ...
... straight line AL is equal to BC . Wherefore , from the given point A , a straight line AL has been drawn equal to the given straight line BC . PROP . III . PROB . From the greater of two given straight lines to cut off a part equal to ...
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Common terms and phrases
ABC is equal ABCD adjacent angles altitude angle ABC angle ACB angle BAC base BC bisected centre chord circle ABC circumference cosine cylinder definition demonstrated described diameter divided draw equal and similar equal angles equiangular equilateral equilateral polygon equimultiples Euclid exterior angle fore four right angles given rectilineal given straight line greater Hence hypotenuse inscribed join less Let ABC Let the straight magnitudes meet opposite angle parallel parallelogram parallelopiped perpendicular polygon prism PROB PROP proportional proposition quadrilateral radius ratio rectangle contained rectilineal figure remaining angle right angled triangle SCHOLIUM segment semicircle shewn side BC sine solid angle solid parallelopiped spherical angle spherical triangle square straight line BC THEOR touches the circle triangle ABC triangle DEF wherefore
Popular passages
Page 51 - If a straight line be divided into two equal parts, and also into two unequal parts; the rectangle contained by the unequal parts, together with the square of the line between the points of section, is equal to the square of half the line.
Page 29 - Straight lines which are parallel to the same straight line are parallel to one another. Triangles and Rectilinear Figures. The sum of the angles of a triangle is equal to two right angles.
Page 12 - 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 11 - Let it be granted that a straight line may be drawn from any one point to any other point. 2. That a terminated straight line may be produced to any length in a straight line. 3. And that a circle may be described from any centre, at any distance from that centre.
Page 72 - To draw a straight line from a given point, either without or in the circumference, which shall touch a given circle. First, let A be a given point without the given circle BCD : it is required to draw a straight line from A which shall touch the circle.
Page 84 - 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.
Page 80 - The angle in a semicircle is a right angle ; the angle in a segment greater than a semicircle is less than a right angle ; and the angle in a segment less than a semicircle is greater than a right angle.
Page 22 - Any two sides of a triangle are together greater than the third side.
Page 53 - If a straight line be divided into any two parts, four times the rectangle contained by the whole line, and one of the parts, together with the square of the other part, is equal to the square of the straight line which is made up of the whole and that part.
Page 35 - Parallelograms upon the same base and between the same parallels, are equal to one another.