document.write( "Question 1039917: Suppose we have a graph of parametric equations x=bsin(t), y=b(cos(t))^3 on where t is on [0,2pi].
\n" ); document.write( "A. Find the point(s) on the given graph where the slope of the tangent line is 3/4. (Find t values not x,y values)
\n" ); document.write( "B. Determine the area, in terms of b, of the region enclosed by the graph.
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Algebra.Com's Answer #654725 by robertb(5830)\"\" \"About 
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A. Find the point(s) on the given graph where the slope of the tangent line is 3/4. (Find t values not x,y values).\r
\n" ); document.write( "\n" ); document.write( "\"x=bsint\" and \"y=b%28cost%29%5E3\"\r
\n" ); document.write( "\n" ); document.write( "==> \"dx%2Fdt+=+b%2Acost\" and \"dy%2Fdt+=+-3b%28cost%29%5E2%2Asint\" after differentiating both x and y wrt t.\r
\n" ); document.write( "\n" ); document.write( "==> \"dy%2Fdx+=+-3sint%2Acost\" after division.\r
\n" ); document.write( "\n" ); document.write( "To find the point(s) on the graph where the slope of the tangent line is 3/4, let \"dy%2Fdx+=+-3sint%2Acost+=+3%2F4\" .\r
\n" ); document.write( "\n" ); document.write( "==> \"-sint%2Acost+=+1%2F4\" ==> \"-2sint%2Acost+=+1%2F2\" ==> \"sin2t+=+-1%2F2\".\r
\n" ); document.write( "\n" ); document.write( "==> \"2t+=+%287%2Api%29%2F6\" or \"2t+=+%2811%2Api%29%2F6\".\r
\n" ); document.write( "\n" ); document.write( "==> \"t+=+%287%2Api%29%2F12\" or \"t+=+%2811%2Api%29%2F12\".\r
\n" ); document.write( "\n" ); document.write( "B. Determine the area, in terms of b, of the region enclosed by the graph.
\n" ); document.write( "To determine the area, first express y in terms of x.\r
\n" ); document.write( "\n" ); document.write( "\"x=bsint\", \"y=b%28cost%29%5E3+\"\r
\n" ); document.write( "\n" ); document.write( "==> \"x%2Fb=sint\", \"%28y%2Fb%29%5E%281%2F3%29=cost+\"
\n" ); document.write( "==> \"x%5E2%2Fb%5E2+%2B+y%5E%282%2F3%29%2Fb%5E%282%2F3%29+=+1\"
\n" ); document.write( "==> \"y%5E%282%2F3%29%2Fb%5E%282%2F3%29+=+1+-x%5E2%2Fb%5E2++=+%28b%5E2+-+x%5E2%29%2Fb%5E2\"
\n" ); document.write( "==> \"y%5E%282%2F3%29=%28b%5E%282%2F3%29%2Fb%5E2%29%2A%28b%5E2+-+x%5E2%29\"
\n" ); document.write( "==> \"y%5E%282%2F3%29=%281%2Fb%5E%284%2F3%29%29%2A%28b%5E2+-+x%5E2%29\"
\n" ); document.write( "==> \"y=%281%2Fb%5E2%29%2A%28b%5E2+-+x%5E2%29%5E%283%2F2%29\" or \"y=%28-1%2Fb%5E2%29%2A%28b%5E2+-+x%5E2%29%5E%283%2F2%29\".\r
\n" ); document.write( "\n" ); document.write( "Now for purpose of getting the area assume that b > 0. (The sense of the graph in this case is clockwise. b < 0 would only change the direction to ccw but would yield the same graph and the same area.)\r
\n" ); document.write( "\n" ); document.write( "==> Area = \"%284%2Fb%5E2%29int%28%28b%5E2+-+x%5E2%29%5E%283%2F2%29%2C+dx%2C+0%2Cb%29\"\r
\n" ); document.write( "\n" ); document.write( "(I wrote it this way rather than \"%282%2Fb%5E2%29int%28%28b%5E2+-+x%5E2%29%5E%283%2F2%29%2C+dx%2C+-b%2Cb%29\". They give the same answer.)\r
\n" ); document.write( "\n" ); document.write( "Let x = bsint.
\n" ); document.write( "==> dx = bcostdt\r
\n" ); document.write( "\n" ); document.write( "==> Area = \r
\n" ); document.write( "\n" ); document.write( "= \r
\n" ); document.write( "\n" ); document.write( "Using \"%28cost%29%5E2+=+%281%2Bcos2t%29%2F2\",\r
\n" ); document.write( "\n" ); document.write( "Area = \"b%5E2%2Aint%28%281%2B2cos2t%2B%28cos2t%29%5E2%29%2C+dt%2C+0%2Cpi%2F2%29+\" \r
\n" ); document.write( "\n" ); document.write( "=\"b%5E2%2Aint%28%281%2B2cos2t%2B%281%2Bcos4t%29%2F2%29%2C+dt%2C+0%2Cpi%2F2%29+\" \r
\n" ); document.write( "\n" ); document.write( "=\"b%5E2%2Aint%28%283%2F2%2B2cos2t%2B%281%2F2%29%2Acos4t%29%2C+dt%2C+0%2Cpi%2F2%29+\" \r
\n" ); document.write( "\n" ); document.write( "=\"b%5E2%2A%28%283%2F2%29t%2B+sin2t+%2B+%281%2F8%29%2Asin4t%29%5B0%5D%5E%28pi%2F2%29\" \r
\n" ); document.write( "\n" ); document.write( "=\"b%5E2%2A%283%2F2%29%2A%28pi%2F2%29+=+%283b%5E2%2Api%29%2F4\"\r
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