document.write( "Question 1025449: Find the total cost of polishing , if it cost 10 php per square meter to polish the lateral surface area of a 10 meter marble monument in the shape of a frustum of a regular pyramid with upper and lower base edges measuring 8 m and 4 m, respectively. \n" ); document.write( "
Algebra.Com's Answer #640872 by KMST(5328)\"\" \"About 
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All length measurements will be in meters, and all surface area measurements will be in square meters, but I will not write the units except at the end.
\n" ); document.write( "The cross-section of that pyramid and frustum would look like this:
\n" ); document.write( " with similar triangles
\n" ); document.write( "The large right triangle has the same angle measures,
\n" ); document.write( "and twice the base (4 rather than 2), compared to the smaller right triangle.
\n" ); document.write( "So, the height of the large right triangle is twice the height of the smaller one,
\n" ); document.write( "meaning that the height of the frustrum (10) and the height of the small triangle are both half of the height of the large triangle ( \"2%2A10=20\" ).
\n" ); document.write( "
\n" ); document.write( "In the large right triangle, the Pythagorean theorem says that
\n" ); document.write( "\"%282x%29%5E2=4%5E2%2B20%5E2\"
\n" ); document.write( "\"%282x%29%5E2=16%2B400\"
\n" ); document.write( "\"%282x%29%5E2=416\"
\n" ); document.write( "\"2x=sqrt%28416%29\" is the slant height of the pyramid.
\n" ); document.write( "The lateral faces of pyramid and frustrum look like this:
\n" ); document.write( " and
\n" ); document.write( "The surface area of each of the lateral faces of the frustum can be calculated as
\n" ); document.write( "\"%28%288%2B4%29%2F2%29%2A%28sqrt%28416%29%2F2%29\"
\n" ); document.write( "The total lateral surface area can be calculated as
\n" ); document.write( "\"4%2A%28%288%2B4%29%2F2%29%2A%28sqrt%28416%29%2F2%29=12sqrt%28416%29\" .
\n" ); document.write( "At 10 php per square meter, the cost for polishing the lateral surface would be
\n" ); document.write( "\"10%2A12%2Asqrt%28416%29=%22approx.%22\"\"highlight%28247.53php%29\" .
\n" ); document.write( "
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