Bion, Nicolas, Traité de la construction et principaux usages des instruments de mathématique, 1723

List of thumbnails

< >
61
61 (47) 		62
62 (48)
63
63 (49) 		64
64 (50)
65
65 (51) 		66
66 (52)
67
67 (53) 		68
68 (54)
69
69 (55) 		70
70 (56)
< >
page |< < (54) of 438 > >|
    <echo version="1.0RC">
      <text xml:lang="fr" type="free">
        <div xml:id="echoid-div212" type="section" level="1" n="80">
          <p>
            <s xml:id="echoid-s1851" xml:space="preserve">
              <pb o="54" file="068" n="68" rhead="CONSTRUCTION ET USAGE"/>
            polygones; </s>
            <s xml:id="echoid-s1852" xml:space="preserve">& </s>
            <s xml:id="echoid-s1853" xml:space="preserve">le compas de proportion demeurant ainſi ouvert, pre-
              <lb/>
            nez l'ouverture des nombres 10, qui ſont ceux du decagone, Cette
              <lb/>
            ouverture donnera D F, qui ſera la mediane, c'eſt à-dire, le plus
              <lb/>
            grand ſegment de la ligne propoſée, puiſque la mediane du raïon
              <lb/>
            d'un cercle coupé en moyene & </s>
            <s xml:id="echoid-s1854" xml:space="preserve">extréme raiſon, eſt la corde de 36
              <lb/>
            degrez, qui eſt la dixiéme partie de ſa circonference.</s>
            <s xml:id="echoid-s1855" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s1856" xml:space="preserve">Que ſi l'on ajoûte cette mediane au raïon du cercle, pour n'en
              <lb/>
            faire qu'une ligne, ledit raïon deviendra la mediane, & </s>
            <s xml:id="echoid-s1857" xml:space="preserve">la corde
              <lb/>
            de 36 degrez ſera le petit ſegment.</s>
            <s xml:id="echoid-s1858" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div214" type="section" level="1" n="81">
          <head xml:id="echoid-head132" xml:space="preserve">USAGE IV.
            <lb/>
          Sur une ligne donnée DF, figure 8. décrire untriangle iſocele,
            <lb/>
          qui ait les angles de ſa baſe doubles de celui du ſommet.</head>
          <p>
            <s xml:id="echoid-s1859" xml:space="preserve">APpliquez la longueur de la ligne donnée à l'ouverture des
              <lb/>
              <note position="left" xlink:label="note-068-01" xlink:href="note-068-01a" xml:space="preserve">Fig. 8.</note>
            nombres 10 marquez de part & </s>
            <s xml:id="echoid-s1860" xml:space="preserve">d'autre ſur la ligne des poly-
              <lb/>
            gones; </s>
            <s xml:id="echoid-s1861" xml:space="preserve">& </s>
            <s xml:id="echoid-s1862" xml:space="preserve">le compas de proportion reſtant ainſi ouvert, prenez
              <lb/>
            l'ouverture des nombres 6, pour avoir la longueur des deux côtez
              <lb/>
            égaux du triangle qu'on veut conſtruire.</s>
            <s xml:id="echoid-s1863" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s1864" xml:space="preserve">Il eſt évident que l'angle du ſommet de ce triangle eſt de 36 de-
              <lb/>
            grez, & </s>
            <s xml:id="echoid-s1865" xml:space="preserve">que chacun des angles de la baſe eſt de 72 degrez; </s>
            <s xml:id="echoid-s1866" xml:space="preserve">or l'an-
              <lb/>
            gle de 36 degrez eſt l'angle du centre d'un decagone.</s>
            <s xml:id="echoid-s1867" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div216" type="section" level="1" n="82">
          <head xml:id="echoid-head133" xml:space="preserve">USAGE V.
            <lb/>
          Ouvrir le compas de proportion, en ſorte que les deux lignes
            <lb/>
          des Polygones faſſent un angle droit.</head>
          <p>
            <s xml:id="echoid-s1868" xml:space="preserve">PRenez avec le compas commun ſur la ligne des polygones la di-
              <lb/>
            ſtance depuis le centre du compas de proportion juſqu'au nom-
              <lb/>
            bre 5, ouvrez enſuite le compas de proportion, de ſorte que cette
              <lb/>
            diſtance ſoit appliquée d'une part ſur le nombre 6, & </s>
            <s xml:id="echoid-s1869" xml:space="preserve">de l'autre part
              <lb/>
            ſur le nombre 10 des deux lignes des polygones, elles feront au cen-
              <lb/>
            tre un angle droit, parce que le quarré du côté du pentagone eſt égal
              <lb/>
            au quarré du côré de l'exagone, & </s>
            <s xml:id="echoid-s1870" xml:space="preserve">au quarré du côté du decagone.</s>
            <s xml:id="echoid-s1871" xml:space="preserve"/>
          </p>
        </div>
        <div xml:id="echoid-div217" type="section" level="1" n="83">
          <head xml:id="echoid-head134" xml:space="preserve">SECTION IV.
            <lb/>
          Des Vſages de la ligne des Cordes.</head>
          <head xml:id="echoid-head135" xml:space="preserve">USAGE I.
            <lb/>
          Ouvrir le compas de proportion de ſorte que les deux lignes des
            <lb/>
          cordes faſſent un angle de tant de degrez qu'on voudra.</head>
          <p>
            <s xml:id="echoid-s1872" xml:space="preserve">PRenez avec un compas ordinaire le long de la ligne des cordes
              <lb/>
            la diſtance depuis le centre de la charniere juſqu'au nombre des
              <lb/>
            </s>
          </p>
        </div>
      </text>
    </echo>
Impressum