document.write( "Question 1072160: ABCD is a cyclic quadrilateral whose diagonals intersect at P such that angle DBC=30 degree and angle BAC=50 degree.
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Algebra.Com's Answer #687065 by Edwin McCravy(20055)\"\" \"About 
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document.write( "An inscribed angle is measured by one-half its intercepted arc.\r\n" );
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document.write( "Inscribed angle ∠CAD and ∠DBC both subtend the same arc CD.\r\n" );
document.write( "So ∠CAD = ∠DBC = 30°\r\n" );
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document.write( "That means ∠BAD = ∠BAC + ∠CAD = 50° + 30° = 80°\r\n" );
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document.write( "Since inscribed angle ∠BAD is measured by one-half its\r\n" );
document.write( "intercepted arc, its intercepted arc BCD = 2(80°) = 160°.\r\n" );
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document.write( "arc BCD + arc BAD = 360°, \r\n" );
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document.write( "   160° + arc BAD = 360°,\r\n" );
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document.write( "          arc BAD = 200°\r\n" );
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document.write( "inscribed angle ∠BCD = 100° since it subtends arc BAD, and\r\n" );
document.write( "has the measure of one-half its intercepted arc.\r\n" );
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document.write( "Edwin
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