document.write( "Question 1207162: the arch of this bridge is an arc of a circle. the arc measures 80 degrees and the bridge spans a 200 meters across a valley. what is the length of the bridge's arch? \n" ); document.write( "

Algebra.Com's Answer #844878 by ikleyn(52810) $\"\"$ $\"About$

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\n" ); document.write( "the arch of this bridge is an arc of a circle. the arc measures 80 degrees
\n" ); document.write( "and the bridge spans a 200 meters across a valley.
\n" ); document.write( "what is the length of the bridge's arch?
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document.write( "Make a sketch.\r\n" );
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document.write( "You have an arc with the center O, the central angle of 80 degrees and the endpoints A and B\r\n" );
document.write( "that are endpoint of the bridge.\r\n" );
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document.write( "Draw the radius from O, which bisects the arc and intersect the horizontal chord \r\n" );
document.write( "at point C.\r\n" );
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document.write( "You have right-angled triangle AOC with one acute angle of 40 degrees and the opposite leg \r\n" );
document.write( "AC of 200/2 = 100 meters long and adjacent leg OC.\r\n" );
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document.write( "The radius of the arc is  R =  =  = 155.5936 m  (rounded).\r\n" );
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document.write( "The length of the bridge is the length of the arc AB and is equal to \r\n" );
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document.write( "     =  =  = 217.25 m (rounded).\r\n" );
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document.write( "ANSWER.  The length of the bridge is about 217.25 meters.\r\n" );
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\n" ); document.write( "\n" ); document.write( "The solution in the post by @MathLover1 is INCORRECT.\r
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