document.write( "Question 1140775: (1) A cirlce is defined by the equation x^2-6x+y^2-2y=6.\r
\n" ); document.write( "\n" ); document.write( "(a) Rewrite the equation of the circle in the form:(x-a)^2+(y-b)^2=r^2\r
\n" ); document.write( "\n" ); document.write( "(b) Write down the coordinates of M,the centre of the circle.\r
\n" ); document.write( "\n" ); document.write( "(c) A tangent PQ is drawn from the point P(6;-2) to the circle, with Q the point of contact.Calculate the length of the tangent PQ.\r
\n" ); document.write( "\n" ); document.write( "Please can someone please help me with the question I begg
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Algebra.Com's Answer #761323 by greenestamps(13200)\"\" \"About 
You can put this solution on YOUR website!


\n" ); document.write( "The answer to part (c) from the other tutor is not for the question that is asked....

\n" ); document.write( "\"x%5E2-6x%2By%5E2-2y=6\"

\n" ); document.write( "Complete the square in x and y to put the equation in standard form

\n" ); document.write( "\"%28x-h%29%5E2%2B%28y-k%29%5E2+=+r%5E2\"

\n" ); document.write( "\"%28x%5E2-6x%29%2B%28y%5E2-2y%29+=+6\"
\n" ); document.write( "\"%28x%5E2-6x%2B9%29%2B%28y%5E2-2y%2B1%29+=+6%2B9%2B1\"
\n" ); document.write( "\"%28x-3%29%5E2+%2B+%28y-1%29%5E2+=+4%5E2\"

\n" ); document.write( "The center is (3,1); the radius is 4.

\n" ); document.write( "We are done with parts (a) and (b) (done correctly by the other tutor).

\n" ); document.write( "(c) A tangent PQ is drawn from the point P(6,-2) to the circle, with Q the point of contact.

\n" ); document.write( "Consider the line determined by M and Q. Let the diameter of the circle contained in that line be AB, with B between M and Q. Then the rule relating the lengths of a tangent and a secant to a circle tell us

\n" ); document.write( "\"PQ%5E2+=+%28PM-MB%29%28PM%2BMA%29\"

\n" ); document.write( "MA and MB are radii of the circle; length 4. MP by the Pythagorean Theorem is 3*sqrt(3). Then

\n" ); document.write( "\"PQ%5E2+=+%283sqrt%283%29-4%29%283sqrt%283%29%2B4%29+=+27-16+=+11\"

\n" ); document.write( "ANSWER: PQ = sqrt(11)
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