Elements of Geometry: With NotesJ. Souter, 1827 - 208 σελίδες |
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Σελίδα 39
... chord of an arc is the straight line joining its extremities . It is said to subtend the arc . 8. A segment of a circle is the por- tion included by an arc and its chord . F E B The space EFGE included by the arc EFG , and the chord EG ...
... chord of an arc is the straight line joining its extremities . It is said to subtend the arc . 8. A segment of a circle is the por- tion included by an arc and its chord . F E B The space EFGE included by the arc EFG , and the chord EG ...
Σελίδα 40
... chord ; and by an angle at the centre is meant one whose vertex is at the centre . In both cases the angles are said to be subtended by the chords or arcs which their sides include . POSTULATE . From any point as a centre with any ...
... chord ; and by an angle at the centre is meant one whose vertex is at the centre . In both cases the angles are said to be subtended by the chords or arcs which their sides include . POSTULATE . From any point as a centre with any ...
Σελίδα 41
... chord is a diameter , is a semi - circumference , and the included segment is a semi - circle . PROPOSITION II ... chords . Cor . 2. If the angle at the centre of BOOK III . 41.
... chord is a diameter , is a semi - circumference , and the included segment is a semi - circle . PROPOSITION II ... chords . Cor . 2. If the angle at the centre of BOOK III . 41.
Σελίδα 42
... chord which it subtends shall also be bisected . Scholium . The above reasoning obviously applies to the case of ... chord AB would coincide with those of the chord DE ; these chords are , there- fore , equal : hence the angle ACB is ...
... chord which it subtends shall also be bisected . Scholium . The above reasoning obviously applies to the case of ... chord AB would coincide with those of the chord DE ; these chords are , there- fore , equal : hence the angle ACB is ...
Σελίδα 43
... chord , or with the middle of the arc , it follows , conversely , that the line joining the centre , and middle of the chord , or the middle of the arc , must be perpendi- cular to the chord . Cor . 2. And a perpendicular , through the ...
... chord , or with the middle of the arc , it follows , conversely , that the line joining the centre , and middle of the chord , or the middle of the arc , must be perpendi- cular to the chord . Cor . 2. And a perpendicular , through the ...
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Συχνά εμφανιζόμενοι όροι και φράσεις
ABCD adjacent angles altitude angle ABC angle ACB angle BAC antecedent base centre chord circ circle circumference circumscribed polygon coincide consequently Prop construction Converse of Prop corollary demonstration described diagonals diameter divided draw enveloping line equal angles equal Prop equimultiples equivalent Euclid exterior angle follows four right angles geometry gonal greater half hence homologous sides hypothenuse hypothesis included angle inscribed angle inscribed polygon intersect isosceles triangle join Legendre less line drawn lines be drawn magnitudes meet multiple number of sides obtuse opposite angles parallel perimeter perpendicular PROBLEM proportion PROPOSITION XII quadrilateral radii rectangle rectangle contained regular polygon respectively equal rhomboid right angled triangle Scholium shorter side BC similar polygons similar triangles submultiple subtended surface tangent THEOREM three angles tiple triangle ABC vertex VIII
Δημοφιλή αποσπάσματα
Σελίδα 159 - ... if a straight line, &c. QED PROPOSITION 29. — Theorem. If a straight line fall upon two parallel straight lines, it makes the alternate angles equal to one another ; and the exterior angle equal to the interior and opposite upon the same side ; and likewise the two interior angles upon the same side together equal to two right angles.
Σελίδα 24 - If there be two straight lines, one of which is divided into any number of parts, the rectangle contained by the two straight lines is equal to the rectangles contained by the undivided line, and the several parts of the divided line. Let...
Σελίδα 80 - IF a straight line be drawn parallel to one of the sides of a triangle, it shall cut the other sides, or those produced, proportionally; and if the sides, or the sides produced, be cut proportionally, the straight line which joins the points of section shall be parallel to the remaining side of the triangle...
Σελίδα 179 - FBC ; and because the two sides AB, BD are equal to the two FB, BC, each to each, and the angle DBA equal to the angle FBC ; therefore the base AD is equal to the base FC, and the triangle ABD to the triangle FBC.
Σελίδα 136 - To describe an isosceles triangle, having each of the angles at the base double of the third angle.
Σελίδα 179 - BK, it is demonstrated that the parallelogram CL is equal to the square HC. Therefore the whole square BDEC is equal to the two squares GB, HC ; and the square BDEC is described upon the straight line BC, and the squares GB, HC upon BA, AC.
Σελίδα 99 - And since a radius drawn to the point of contact is perpendicular to the tangent, it follows that the angle included by two tangents, drawn from the same point, is bisected by a line drawn from the centre of the circle to that point ; for this line forms the hypotenuse common to two equal right angled triangles. PROP. XXXVII. THEOR. If from a point without a circle there be drawn two straight lines, one of which cuts the circle, and the other meets it ; if the rectangle...
Σελίδα 29 - In any triangle, the square of a side opposite an acute angle is equal to the sum of the squares of the other two sides diminished by twice the product of one of those sides and the projection of the other side upon it.
Σελίδα 179 - FC, and the triangle ABD to the triangle FBC. Now the parallelogram BL is double...
Σελίδα 165 - This formula already proves, that if two angles of one triangle are equal to two angles of another, the third angle of the former must also be equal to the third of the latter ; and this granted, it is easy to arrive at the theorem we have in view.