document.write( "Question 1099730: Find the equation of the line tangent to the circle x2 + y2 = 25 at point (3,4) \n" ); document.write( "

Algebra.Com's Answer #714260 by ikleyn(52787) $\"\"$ $\"About$

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\n" ); document.write( "YOU DO NOT NEED CALCULUS to answer this question.\r
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\n" ); document.write( "\n" ); document.write( "Elementary algebra PLUS Elementary geometry is fully enough !.
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document.write( "The vector from the center (which is the coordinate origin) to the tangent point is (x,y) = (3,4).\r\n" );
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document.write( "Its slope is .\r\n" );
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document.write( "The tangent line is perpendicular to the radius drawn to the tangent point.\r\n" );
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document.write( "Hence, the tangent line has the slope .\r\n" );
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document.write( "Then the equation of the tangent line is  y - 4 = ,  or, after multiplying both sides by 4,  4y - 16 = (-3)*(x-3),\r\n" );
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document.write( "or, equivalently,  3x + 4y = 25.\r\n" );
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document.write( "What's it.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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