document.write( "Question 1016364: The ellipse \"+x%5E2%2F64+%2B+y%5E2%2F25+=+1\" is given. Find the equations of the lines tangent to this ellipse which make an angle of 60 degrees with the x-axis.\r
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Algebra.Com's Answer #632760 by Alan3354(69443)\"\" \"About 
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The ellipse \"+x%5E2%2F64+%2B+y%5E2%2F25+=+1\" is given. Find the equations of the lines tangent to this ellipse which make an angle of 60 degrees with the x-axis.
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\n" ); document.write( "\"+x%5E2%2F64+%2B+y%5E2%2F25+=+1\"
\n" ); document.write( "Find the slope of the ellipse at any point.
\n" ); document.write( "Slope m = dy/dx
\n" ); document.write( "\"+x%5E2%2F64+%2B+y%5E2%2F25+=+1\"
\n" ); document.write( "Differentiate implicitly
\n" ); document.write( "(x/32) dx + (2y/25)dy = 0
\n" ); document.write( "dy/dx = -25x/(64y)
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\n" ); document.write( "The slope of 60 degs with the x-axis is tan(60) = sqrt(3)
\n" ); document.write( "---
\n" ); document.write( "--> \"-25x%2F%2864y%29+=+sqrt%283%29\"
\n" ); document.write( "\"x+=+-+64%2Asqrt%283%29y%2F25\"
\n" ); document.write( "\"+x%5E2%2F64+%2B+y%5E2%2F25+=+1\" --> \"25x%5E2+%2B+64y%5E2+=+1600\"
\n" ); document.write( "Sub for x in \"25x%5E2+%2B+64y%5E2+=+1600\"
\n" ); document.write( "---
\n" ); document.write( "\"4096%2A3y%5E2%2F25+%2B+64y%5E2+=+1600\"
\n" ); document.write( "\"12288y%5E2+%2B+1600y%5E2+=+40000%7D%7D%0D%0A%7B%7B%7B13888y%5E2+=+40000\"
\n" ); document.write( "\"217y%5E2+=+625\"
\n" ); document.write( "\"y%5E2+=+625%2F217\"
\n" ); document.write( "Sub for y^2 in \"25x%5E2+%2B+64y%5E2+=+1600\" to find x^2
\n" ); document.write( "x^2 = 12288/217 = 4096*3/217
\n" ); document.write( "\"x+=+%2B64%2Asqrt%283%2F217%29\"
\n" ); document.write( "\"x+=+-64%2Asqrt%283%2F217%29\"
\n" ); document.write( "Solve \"25x%5E2+%2B+64y%5E2+=+1600\" for y^2
\n" ); document.write( "\"y%5E2+=+625%2F217\"
\n" ); document.write( "\"y+=+%2B25%2Fsqrt%28217%29\"
\n" ); document.write( "\"y+=+-25%2Fsqrt%28217%29\"
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\n" ); document.write( "For +60 degs with the x-axis, when x is +, y is negative, and vice versa.
\n" ); document.write( "The tangent points are:
\n" ); document.write( "(+64*sqrt(3/217),-25/sqrt(217))
\n" ); document.write( "--> y + (25/sqrt(217)) = sqrt(3)*(x - 64*sqrt(3/217))
\n" ); document.write( "and
\n" ); document.write( "(-64*sqrt(3/217),+25/sqrt(217))
\n" ); document.write( "--> y - (25/sqrt(217)) = sqrt(3)*(x + 64*sqrt(3/217))
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