document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1163747>Question 1163747</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Circles centered at A and B are tangent at T.  Prove that A,T, andB are collinear. </SPAN>\n" );
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document.write( "Let TU be the common tangent line.<br><BR>\n" );
document.write( "Radii AT and BT of the two circles are both perpendicular to TU, so angles ATU and BTU are both 90 degrees.<br><BR>\n" );
document.write( "That makes angle ATB 180 degrees; and that makes A, T, and B collinear.<br><BR>\n" );
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