## Euclid's Elements of geometry, books i. ii. iii. iv |

### Inni boken

Side 1

When a 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

When a 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

**perpendicular**to it . 11. Side 14

To draw a straight line

To draw a straight line

**perpendicular**to a given straight line of unlimited length , from a given point without it . ( References - Prop . I. 8 , 10 ; post . 3 ; def . 10 , 15. ) Given.- Let AB be the given straight line , which may be ... Side 15

It is required to draw from the point C , a straight line

It is required to draw from the point C , a straight line

**perpendicular**to AB . Construction . - 1 . Take any point D upon the other side of AB . 2. From the centre C , at the distance CD , describe the circle EGF , meeting AB in F and ... Side 47

The straight line drawn from the vertex of an isosceles triangle to the point of bisection of the base , bisects the vertical angle , and is

The straight line drawn from the vertex of an isosceles triangle to the point of bisection of the base , bisects the vertical angle , and is

**perpendicular**to the base . 4. In the figure to Euc . I. 5 , if a straight line be drawn from A ... Side 48

The straight lines which bisect the three sides of a triangle

The straight lines which bisect the three sides of a triangle

**perpendicularly**all meet in the same point . 8. ... To draw a straight line**perpendicular**to a given straight line , from its extremity , without producing it . 16.### Hva folk mener - Skriv en omtale

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ABCD angle ABC angle BAC angle BCD angle equal assumed base base BC BC is equal bisected BOOK centre circle ABC circumference coincide common Conclusion Conclusion.—Therefore const Construction Construction.-1 Demonstration Demonstration.-1 describe diameter distance divided double draw drawn equal exterior angle extremities fall figure four given circle given point given straight line greater half Hypothesis Hypothesis.—Let impossible inscribed join less manner meet opposite angles parallel parallelogram pass perpendicular produced proved Q. E. D. PROPOSITION reason rectangle contained rectilineal figure References-Prop right angles segment semicircle Sequence.—The shown sides square on AC straight line AC Take third touches the circle triangle ABC twice the rectangle whole

### Populære avsnitt

Side 25 - 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.

Side 2 - 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.

Side 99 - 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.

Side 4 - 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...

Side 66 - ... the sides containing the obtuse angle, by twice the rectangle contained by the side upon which, when produced, the perpendicular falls, and the straight line intercepted without the triangle between the perpendicular and the obtuse...

Side 65 - To divide a given straight line into two parts, so that the rectangle contained by the whole, and one of the parts, may be equal to the square of the other part.

Side 32 - F, which is the common vertex of the triangles ; that is, together with four right angles. Therefore all the angles of the figure, together with four right angles, are equal to twice as many right angles as the figure has sides.

Side 58 - If a straight line be bisected, and produced to any point ; the rectangle contained by the whole line thus produced, and the part of it produced...

Side 88 - The straight line drawn at right angles to the diameter of a circle, from the extremity of it, falls without the circle...

Side 33 - The straight lines which join the extremities of two equal and parallel straight lines towards the same parts, are also themselves equal and parallel.