<s xml:id="echoid-s20642" xml:space="preserve">deſcribet ſemicirculum in ſuperficie coni. </s>
<s xml:id="echoid-s20643" xml:space="preserve">ipſe tandem ſemicirculus a d e.
<lb/>
</s>
<s xml:id="echoid-s20644" xml:space="preserve">poſt motum ſuum collocetur in loco, ubi lineæ cadentes concurrunt, & </s>
<s xml:id="echoid-s20645" xml:space="preserve">trigonum, quod contra mouetur habeat
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hanc poſitionem d l a, & </s>
<s xml:id="echoid-s20646" xml:space="preserve">ſignum in quo incidunt, ſit k. </s>
<s xml:id="echoid-s20647" xml:space="preserve">deſcribatur etiam per b. </s>
<s xml:id="echoid-s20648" xml:space="preserve">ſemicirculus b m f. </s>
<s xml:id="echoid-s20649" xml:space="preserve">
<lb/>
& </s>
<s xml:id="echoid-s20650" xml:space="preserve">commune ſegmentum eius, & </s>
<s xml:id="echoid-s20651" xml:space="preserve">circuli b d f a. </s>
<s xml:id="echoid-s20652" xml:space="preserve">ſit b f. </s>
<s xml:id="echoid-s20653" xml:space="preserve">inde aſigno k. </s>
<s xml:id="echoid-s20654" xml:space="preserve">adſuperficiem ſemcirculi b
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d a. </s>
<s xml:id="echoid-s20655" xml:space="preserve">cadat perpendicularis, certum eſt quod in circuli ſuperficiem cadet, quoniam in ſuperficie circuli eiuſ-