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    Hello, <br>
    <br>
    I try to make this exercise : <br>
    <br>
    <div class="SIntrapara"><a name="(counter._mix._(exercise._mix4))"></a><span
        style="font-weight: bold;">Exercise</span> 76: A programmer has
      chosen to represent locations as Cartesian points or just points:</div>
    <div class="SIntrapara">
      <blockquote class="SCodeFlow">
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              <td><span class="RktCmt">;</span><span class="RktCmt"> </span><span
                  class="RktCmt">Location is one of:</span></td>
            </tr>
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              <td><span class="RktCmt">;</span><span class="RktCmt"> </span><span
                  class="RktCmt">&#8211;</span><span class="RktCmt"> Posn</span></td>
            </tr>
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              <td><span class="RktCmt">;</span><span class="RktCmt"> </span><span
                  class="RktCmt">&#8211;</span><span class="RktCmt"> Number</span></td>
            </tr>
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              <td><span class="RktCmt">;</span><span class="RktCmt"> </span><span
                  class="RktCmt">interp. Posn are positions on the
                  Cartesian grid,</span></td>
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              <td><span class="RktCmt">;</span><span class="RktCmt"> </span><span
                  class="RktCmt">Numbers are positions on the number
                  line </span></td>
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      </blockquote>
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    <div class="SIntrapara">Design the function <span class="RktSym">in-reach</span>,
      which determines whether or not a given location&#8217;s distance to the
      origin is strictly less than some constant<span class="RktSym">R</span>.<br>
      <br>
      So I must design a function called in-reach.<br>
      <br>
      Am I right I need to use two structs (Posn) . One for the given
      location and one for the origon ?<br>
      <br>
      Regards, <br>
      <br>
      Roelof<br>
      <br>
      <br>
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