Question 1190528
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Here is the operative geometry principle:<br><pre>
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When two tangents or secants from an external point intersect a circle,
the measure of the angle between the tangents or secants is half the
difference between the measures of the two intercepted arcs
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In this problem with two tangents, the two tangents divide the whole circle into two arcs with arc lengths x and (360-x) degrees.<br>
So the 80 degree measure of the given angle is half the difference between the measures of those two arcs:<br>
{{{80 = ((360-x)-x)/2}}}<br>
Solve using basic algebra....<br>