document.write( "Question 672444: Find an equation of the circle whose diameter has endpoints (-5,6) and (-3,-4) \n" ); document.write( "
Algebra.Com's Answer #418054 by DrBeeee(684)\"\" \"About 
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The center of the circle is in the \"middle\" of the diameter which is the average of the end points.
\n" ); document.write( "The x co-ordinant of the center of the circle is
\n" ); document.write( "(1) x = (-5 + -3)/2 or
\n" ); document.write( "(2) x = -4
\n" ); document.write( "The y co-ordinant of the center of the circle is
\n" ); document.write( "(3) y = (6 + (-4))/2 or
\n" ); document.write( "(4) y = 1
\n" ); document.write( "This gives us part of the circle equation as
\n" ); document.write( "(5) (x+4)^2 + (y-1)^2 = r^2
\n" ); document.write( "Now we need to find r. Let's get the diameter first by using
\n" ); document.write( "(6) d^2 = ((-3-(-5))^2 + (6 - (-4))^2 or
\n" ); document.write( "(7) d^2 = 2^2 + 10^2 or
\n" ); document.write( "(8) d^2 = 104.
\n" ); document.write( "Using d = 2r we get
\n" ); document.write( "(9) 4*r^2 = 104 or
\n" ); document.write( "(10) r^2 = 104/4 or
\n" ); document.write( "(11) r^2 = 26
\n" ); document.write( "The final equation of the circle is
\n" ); document.write( "(12) (x+4)^2 + (y-1)^2 = 26 \n" ); document.write( "
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