document.write( "Question 1092255: You measure the shadow cast by a certain tall building and find that it is 90 feet long. Then you measure the shadow cast by a three-foot post and find it to be 4 inches long. Determine the building's height. \r
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Algebra.Com's Answer #706866 by MathTherapy(10552) $\"\"$ $\"About$

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You measure the shadow cast by a certain tall building and find that it is 90 feet long. Then you measure the shadow cast by a three-foot post and find it to be 4 inches long. Determine the building's height. \r
\n" ); document.write( "\n" ); document.write( "I wrote it as x/90= 3/4 so 4x=90(3) but my answer was wrong. X= 67.5 (or 68)
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The height of the building, and its shadow are proportionate to the height of the post and its shadow. 
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document.write( "This results in: 
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document.write( "   
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document.write( "Let the building's height be H 
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document.write( "We don't have to change the units, so we keep them in FEET 
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document.write( "The above becomes: 
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document.write( " ------Cross-multiplying
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document.write( "Height of building, or 
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document.write( "Good try!! Everything you did was correct, with the exception that you made an error when you used 4 FEET for the shadow of the post, 
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document.write( "as opposed to .
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document.write( "FYI: You most certainly DO NOT NEED TO USE TRIG ratios to get the height. You already  know that anyway.
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document.write( "It's just that your setup had 4 feet instead of 4 inches.
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document.write( "IGNORE all that COMPLEX solution as it's TOTALLY, TOTALLY UNNECESSARY. \n" );
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