document.write( "Question 913268: On the hyperbola x^2/24-y^2/18=1 find the point M1 nearest to the line 3x+2y+1=0, and compute the distance d from M1 to the line. \n" ); document.write( "
Algebra.Com's Answer #554443 by Fombitz(32388)\"\" \"About 
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The shortest distance would be a perpendicular line from the line, \"3x%2B2y%2B1=0\"
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\n" ); document.write( "\"2y=-3x-1\"
\n" ); document.write( "\"y=-%283%2F2%29x-1%2F2\"
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\n" ); document.write( "A point on the hyperbola that had the same slope would be at the minimum distance.
\n" ); document.write( "Find the slope of the hyperbola by differentiating,
\n" ); document.write( "\"x%5E2%2F24-y%5E2%2F18=1\"
\n" ); document.write( "\"%281%2F24%29%282xdx%29-%281%2F18%29%282ydy%29=0\"
\n" ); document.write( "\"%28xdx%29%2F12=%28ydy%29%2F9\"
\n" ); document.write( "\"dy%2Fdx=%283x%29%2F%284y%29=-3%2F2\"
\n" ); document.write( "\"6x=-12y\"
\n" ); document.write( "\"x=-2y\"
\n" ); document.write( "Substitute into the hyperbola equation,
\n" ); document.write( "\"%28-2y%29%5E2%2F24-y%5E2%2F18=1\"
\n" ); document.write( "\"y%5E2%2F6-y%5E2%2F18=1\"
\n" ); document.write( "\"%283%2F18%29y%5E2-%281%2F18%29y%5E2=1\"
\n" ); document.write( "\"%282%2F18%29y%5E2=1\"
\n" ); document.write( "\"y%5E2=9\"
\n" ); document.write( "\"y=-3\" and \"y=3\"
\n" ); document.write( "Then,
\n" ); document.write( "\"x%5E2%2F24-9%2F18=1\"
\n" ); document.write( "\"x%5E2%2F24=3%2F2\"
\n" ); document.write( "\"x%5E2=36\"
\n" ); document.write( "\"x=6\" and \"x=-6\"
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\n" ); document.write( "So the two points are (-6,3) and (6,-3).
\n" ); document.write( "Now the perpendicular line that would be the shortest distance to the original line has a slope that is the negative reciprocal of the original line.
\n" ); document.write( "\"m=2%2F3\"
\n" ); document.write( "You have the slope and the point, find the line.
\n" ); document.write( "\"y-3=%282%2F3%29%28x-%28-6%29%29\"
\n" ); document.write( "\"y-3=%282%2F3%29%28x%2B6%29\"
\n" ); document.write( "\"y-3=%282%2F3%29x%2B4\"
\n" ); document.write( "\"y=%282%2F3%29x%2B7\"
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\n" ); document.write( "Now find the intersection point of the two lines to find the other point to use to calculate minimum distance.
\n" ); document.write( "\"y=-%283%2F2%29x-1%2F2\"
\n" ); document.write( "\"y=%282%2F3%29x%2B7\"
\n" ); document.write( "\"-%283%2F2%29x-1%2F2=%282%2F3%29x%2B7\"
\n" ); document.write( "Multiply both side by \"6\".
\n" ); document.write( "\"-9x-3=4x%2B42\"
\n" ); document.write( "\"-13x=45\"
\n" ); document.write( "\"highlight%28x=-45%2F13%29\"
\n" ); document.write( "Then,
\n" ); document.write( "\"y=%282%2F3%29%28-45%2F13%29%2B7\"
\n" ); document.write( "\"y=-%2830%2F13%29%2B91%2F13\"
\n" ); document.write( "\"highlight%28y=61%2F13%29\"
\n" ); document.write( "So now use the distance formula,
\n" ); document.write( "\"D%5E2=%28-6-%28-45%2F13%29%29%5E2%2B%283-61%2F13%29%5E2\"
\n" ); document.write( "\"D%5E2=%28-78%2F13%2B45%2F13%29%5E2%2B%2839%2F13-61%2F13%29%5E2\"
\n" ); document.write( "\"D%5E2=%28-33%2F13%29%5E2%2B%2822%2F13%29%5E2\"
\n" ); document.write( "\"D%5E2=%281089%2F169%29%2B%28484%2F169%29\"
\n" ); document.write( "\"D%5E2=1573%2F169\"
\n" ); document.write( "\"D=sqrt%281573%29%2F13\"
\n" ); document.write( "\"highlight%28D=%2811%2F13%29sqrt%2813%29%29\"
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\n" ); document.write( "\n" ); document.write( "You can also calculate the other point that intersects with (6,-3) and then calculate the distance.
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