Question 1115633
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<pre>
x^2 = 20*(20+25) = 20*45 = 900  ====>  x = 30    <U>ANSWER</U>.


    If a tangent and a secant lines are released from a point outside a circle,  then the product of the measures of the secant 
    and its external part is equal to the square of the tangent segment. 
</pre>

See the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/Circles/Metric-relations-for-a-tangent-and-a-secant-lines-released-from-a-point-outside-a-circle.lesson>Metric relations for a tangent and a secant lines released from a point outside a circle</A>, &nbsp;Theorem 1

in this site.


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Also, &nbsp;you have this free of charge online textbook on Geometry

&nbsp;&nbsp;&nbsp;&nbsp;<A HREF=https://www.algebra.com/algebra/homework/Triangles/GEOMETRY-your-online-textbook.lesson>GEOMETRY - YOUR ONLINE TEXTBOOK</A> 

in this site.


The referred lesson is the part of this online textbook under the topic &nbsp;"<U>Properties of circles, inscribed angles, chords, secants and tangents </U>".



Save the link to this online textbook together with its description


Free of charge online textbook in GEOMETRY
https://www.algebra.com/algebra/homework/Triangles/GEOMETRY-your-online-textbook.lesson


to your archive and use it when it is needed.