document.write( "Question 1136847: I am trying to figure out how the area of a right trapezoid and the shorter base was calculated. From a diagram, the longer base is 8cm. The shorter base is unknown. The height is 3 cm. The slant height is 5 cm. I do not know how the total area was calculated at 18cm (squared) and the shorter base was calculated at 4 cm. \n" ); document.write( "
Algebra.Com's Answer #754667 by Theo(13342)\"\" \"About 
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the longer base is equal to 8 cm.
\n" ); document.write( "the height is equal to 3 cm.
\n" ); document.write( "the slant height is equal to 5 cm.\r
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\n" ); document.write( "\n" ); document.write( "if it is a right trapezoid, then two of the angles have to be right angles.\r
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\n" ); document.write( "\n" ); document.write( "label your trapezoid ABCDE clockwise from top left.\r
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\n" ); document.write( "\n" ); document.write( "angle A and angle E are right angles.\r
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\n" ); document.write( "\n" ); document.write( "the slant height is side BC = 5.\r
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\n" ); document.write( "\n" ); document.write( "the height is BD = 3 and AE = 3.\r
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\n" ); document.write( "\n" ); document.write( "the triangle on the right is right triangle BCD where the 90 degree angle is BDC.\r
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\n" ); document.write( "\n" ); document.write( "angles BDE and ABD are also right angles.\r
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\n" ); document.write( "\n" ); document.write( "use pythagorus to find the length of DC, which is 4.\r
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\n" ); document.write( "\n" ); document.write( "pythagorus says 3^2 + x^2 = 5^2\r
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\n" ); document.write( "\n" ); document.write( "solve for x to get x = sqrt(5^2 - 3^2) = sqrt(16) = 4.\r
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\n" ); document.write( "\n" ); document.write( "that makes ED = 4 and, consequently AB = 4 because ABDE forms a rectangle.\r
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\n" ); document.write( "\n" ); document.write( "the area of the trapezoid is equal to the area of the rectangle plus the area of the triangle.\r
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\n" ); document.write( "\n" ); document.write( "this becomes 4 * 3 + 1/2 * 3 * 4 which becomes 12 + 6 = 18.\r
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\n" ); document.write( "\n" ); document.write( "here's my diagram.\r
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