document.write( "Question 1209547: Find the surface area of the regular pyramid.\r
\n" ); document.write( "\n" ); document.write( "A triangular pyramid. The base triangle has a base of 7 centimeters and a height of 6 centimeters. The height of a triangular face is labeled 9 centimeters.\r
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Algebra.Com's Answer #849410 by ikleyn(52803) $\"\"$ $\"About$

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\n" ); document.write( "Find the surface area of the regular pyramid.\r
\n" ); document.write( "\n" ); document.write( "A triangular pyramid. The base triangle has a base of 7 centimeters and a height of 6 centimeters.
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document.write( "In this problem, surface area is the sum of the area of the base triangle and\r\n" );
document.write( "the area of three lateral triangle.\r\n" );
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document.write( "The area of any triangle is half the product of the length of its base (= some side) and the length \r\n" );
document.write( "of the altitude drawn to this side\r\n" );
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document.write( "    area = .\r\n" );
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document.write( "For the base triangle, you are given b= 7 cm, h= 6 cm, so its area is  \r\n" );
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document.write( "     = 7*3 = 21 cm^2.\r\n" );
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document.write( "For three lateral triangles, their areas are equal (since the triangles are congruent).\r\n" );
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document.write( "Using the same rule, you find the area of each triangle  = 63/2 = 31.5 cm^2.\r\n" );
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document.write( "So, the total surface are is\r\n" );
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document.write( "    21 + 3*31.5 = 115.5 cm^2.\r\n" );
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document.write( "It is the answer to your question.\r\n" );
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