. Proposition 12 is mentioned explicitly at the top of the page. The work continues with Proposition 13 below the dividing line. </s>
<lb/>
<quote xml:lang="lat">
<s xml:space="preserve">
Propositio XII.
<lb/>
Data media trium proportionalium et differentia extremarum, invenire </s>
</quote>
<lb/>
<quote>
<s xml:space="preserve">
Given three proportionals and the difference of the extremes, to find the </s>
</quote>
<lb/>
<quote xml:lang="lat">
<s xml:space="preserve">
Propositio XII.
<lb/>
Data media trium proportionalium & adgregato extremarum, invenire </s>
</quote>
<lb/>
<quote>
<s xml:space="preserve">
Given three proportionals and the sum of the extremes, to find the </s>
</quote>
<lb/>
<s xml:space="preserve">
In both of these propositions, Viète showed how the standard construction for three proportionals
can lead to the given equation.
Harriot works the other way round: beginning from an equation,
he gives a construction that represents the same relationship geometrically.
This is what he means by 'effectio æquationis' or 'the construction of an </s>
<s xml:space="preserve">]</s>
</p>
</div>
<head xml:space="preserve" xml:lang="lat">
In Effectiones Geometricas. prop. 12 ex 9 et
<lb/>
[
<emph style="bf">Translation: </emph>
From Effectiones Geometricas, Proposition XII, from pages 9 and ]</head>
<p xml:lang="">
<s xml:space="preserve">
Data media trium proportionalium et differentia extremarum: invenire
<lb/>
<lb/>
[
<emph style="bf">Translation: </emph>
Given the mean of three proportionals and thd difference of the extremes, find the ]</s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Data.
<lb/>
Media.
<lb/>
Differentia.
<lb/>
<lb/>
[
<emph style="bf">Translation: </emph>
Given.
<lb/>
Mean.
<lb/>
Difference.
<lb/>
]</s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Data Media trium proportionalium et
<lb/>
aggregato extremarum: invenire
<lb/>
[
<emph style="bf">Translation: </emph>
Given the mean of three proportionals and the sum of the extremes, find the ]</s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Data.
<lb/>
Media.
<lb/>
Adgreg.
<lb/>
<lb/>
[
<emph style="bf">Translation: </emph>
Given.
<lb/>
Mean.
<lb/>
Sum.
<lb/>
]</s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Methodus ad exhibenda quæsita
<lb/>
in numeris.
<lb/>
Dimidium
<lb/>
Subtrahe
<math>
<mstyle>
<msqrt>
<mrow>
<mn>3</mn>
<mn>6</mn>
</mrow>
</msqrt>
</mstyle>
</math>
id est
<math>
<mstyle>
<mi>D</mi>
<mi>F</mi>
</mstyle>
</math>
<lb/>
vel
<math>
<mstyle>
<mi>A</mi>
<mi>I</mi>
</mstyle>
</math>
. pro
<math>
<mstyle>
<mi>G</mi>
<mi>I</mi>
</mstyle>
</math>
.
Adde pro
<math>
<mstyle>
<mi>I</mi>
<mi>H</mi>
</mstyle>
</math>
<lb/>
Multiplica
<math>
<mstyle>
<mi>I</mi>
<mi>H</mi>
</mstyle>
</math>
<lb/>
per
<math>
<mstyle>
<mi>G</mi>
<mi>I</mi>
</mstyle>
</math>
. et erit
<lb/>
Hoc est.
<lb/>
Cuius radix.
<lb/>
Ergo
<math>
<mstyle>
<mi>A</mi>
<mi>C</mi>
</mstyle>
</math>
<math>
<mstyle>
<mn>6</mn>
<mfrac>
<mrow>
<mn>1</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
vel
<math>
<mstyle>
<mfrac>
<mrow>
<mn>1</mn>
<mn>3</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
<math>
<mstyle>
<mfrac>
<mrow>
<mn>5</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
<math>
<mstyle>
<mi>I</mi>
<mi>D</mi>
</mstyle>
</math>
est
<math>
<mstyle>
<mi>F</mi>
<mi>C</mi>
</mstyle>
</math>
.
<math>
<mstyle>
<mn>4</mn>
</mstyle>
</math>
. prima proportionalis.
<lb/>
<math>
<mstyle>
<mfrac>
<mrow>
<mn>1</mn>
<mn>3</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
plus
<math>
<mstyle>
<mfrac>
<mrow>
<mn>5</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
est
<math>
<mstyle>
<mi>B</mi>
<mi>F</mi>
</mstyle>
</math>
.
<math>
<mstyle>
<mn>9</mn>
</mstyle>
</math>
. tertia
<lb/>
[
<emph style="bf">Translation: </emph>
A method of showing the sought quantities in numbers.
<lb/>
Halve.
<lb/>
Subtract
<math>
<mstyle>
<msqrt>
<mrow>
<mn>3</mn>
<mn>6</mn>
</mrow>
</msqrt>
</mstyle>
</math>
, that is
<math>
<mstyle>
<mi>D</mi>
<mi>F</mi>
</mstyle>
</math>
, or
<math>
<mstyle>
<mi>A</mi>
<mi>I</mi>
</mstyle>
</math>
for
<math>
<mstyle>
<mi>G</mi>
<mi>I</mi>
</mstyle>
</math>
.
<lb/>
Add for
<math>
<mstyle>
<mi>I</mi>
<mi>H</mi>
</mstyle>
</math>
<lb/>
Multiply
<math>
<mstyle>
<mi>I</mi>
<mi>H</mi>
</mstyle>
</math>
by
<math>
<mstyle>
<mi>G</mi>
<mi>I</mi>
</mstyle>
</math>
and it will be
<lb/>
That is
<lb/>
Whose root is
<lb/>
Therefore
<math>
<mstyle>
<mi>A</mi>
<mi>C</mi>
</mstyle>
</math>
(
<math>
<mstyle>
<mn>6</mn>
<mfrac>
<mrow>
<mn>1</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
or
<math>
<mstyle>
<mfrac>
<mrow>
<mn>1</mn>
<mn>3</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
) minus
<math>
<mstyle>
<mi>I</mi>
<mi>D</mi>
</mstyle>
</math>
(
<math>
<mstyle>
<mfrac>
<mrow>
<mn>5</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
<mi>I</mi>
<mi>D</mi>
</mstyle>
</math>
) is
<math>
<mstyle>
<mi>F</mi>
<mi>C</mi>
</mstyle>
</math>
, or
<math>
<mstyle>
<mn>4</mn>
</mstyle>
</math>
, the first proportional.
<lb/>
<math>
<mstyle>
<mfrac>
<mrow>
<mn>1</mn>
<mn>3</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
plus
<math>
<mstyle>
<mfrac>
<mrow>
<mn>5</mn>
</mrow>
<mrow>
<mn>2</mn>
</mrow>
</mfrac>
</mstyle>
</math>
is
<math>
<mstyle>
<mi>B</mi>
<mi>F</mi>
</mstyle>
</math>
, or
<math>
<mstyle>
<mn>9</mn>
</mstyle>
</math>
, the third proportional. </s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Brevius.
<lb/>
Et est accurate
<lb/>
modus
<lb/>
[
<emph style="bf">Translation: </emph>
More briefly.
<lb/>
And it is precisely the ancient ]</s>
</p>
<p xml:lang="">
<s xml:space="preserve">
Poste.
<lb/>
Etsi modus operandi videtur specie quadam differe antiquo
<lb/>
consideranti tamen, et operanti per commpendium; est omnino
<lb/>
[
<emph style="bf">Translation: </emph>
Postscript.
<lb/>
Although the mode of operation seems in certain respects to differ from the ancient way,
nevertheless examined, and carried out more briefly, it is exactly the same.</s>