document.write( "Question 1179955: Find the equation of the line tangent to the circle at the indicated point.
\n" ); document.write( "x^2+y^2-6x+8y-144 = 0 at point (8,8) \n" ); document.write( "

Algebra.Com's Answer #809541 by ikleyn(52788) $\"\"$ $\"About$

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document.write( "You can directly differentiate the equation\r\n" );
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document.write( "    2x*dx + 2y*dy -6*dx + 8*dy = 0\r\n" );
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document.write( "    (2x-6)dx + (2y+8)dy = 0\r\n" );
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document.write( "    (2x-6)dx = -(2y+8)dy\r\n" );
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document.write( "     = \r\n" );
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document.write( "Now substitute the given values (coordinates) into the formula to get the slope\r\n" );
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document.write( "     =  =  = -.\r\n" );
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document.write( "So, now you know the point (8,8) and the slope .\r\n" );
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document.write( "Hence, an equation of the tangent line is\r\n" );
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document.write( "    y - 8 = .      ANSWER\r\n" );
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document.write( "And you can transform it equivalently to any other form you wish.\r\n" );
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