Question 1158194
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The arc is 72 degrees, so the central angle is 72 degrees.<br>
Draw the segment from the center of the circle perpendicular to chord AB.  That segment bisects the 72 degree central angle; it also bisects chord AB.<br>
Then in either of the two right triangles we have<br>
{{{sin(36) = (AB/2)/8}}}<br>
Use a calculator (or the value of sin(36), if you know it) to solve for the length AB.<br>