document.write( "Question 1192295: The graph of $(x-3)^2 + (y-5)^2=16$ is reflected over the line $y=2$. The new graph is the graph of the equation $x^2 + Bx + y^2 + Dy + F = 0$ for some constants $B$, $D$, and $F$. Find $B+D+F$. \n" ); document.write( "
Algebra.Com's Answer #824207 by math_tutor2020(3817)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "The circle template in general is \n" ); document.write( "(x-h)^2 + (y-k)^2 = r^2 \n" ); document.write( "with (h,k) as the center and r = radius.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "For this particular problem \n" ); document.write( "(x-3)^2+(y-5)^2 = 16 \n" ); document.write( "we have (h,k) = (3,5) as the center and r = 4 as the radius.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The point (3,5) is exactly 3 units above the horizontal line y = 2 \n" ); document.write( "When reflecting over this line, we'll move down 3 units to arrive at the mirror line itself, then move another 3 units further south to get to (3,-1). \n" ); document.write( "Overall we moved the center down 6 units. \n" ); document.write( "The radius stays the same because lengths and distances are preserved under reflection operations. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore we go from \n" ); document.write( "(x-3)^2+(y-5)^2 = 16 \n" ); document.write( "to \n" ); document.write( "(x-3)^2+(y+1)^2 = 16 \n" ); document.write( "after reflecting the circle over the horizontal line y = 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's expand things out and get everything to one side. \n" ); document.write( "(x-3)^2+(y+1)^2 = 16 \n" ); document.write( "x^2-6x+9+y^2+2y+1 = 16 \n" ); document.write( "x^2-6x+9+y^2+2y+1-16 = 0 \n" ); document.write( "x^2-6x+y^2+2y-6 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Comparing that last equation to \n" ); document.write( "x^2 + Bx + y^2 + Dy + F = 0 \n" ); document.write( "shows that \n" ); document.write( "B = -6 \n" ); document.write( "D = 2 \n" ); document.write( "F = -6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So, \n" ); document.write( "B+D+F = -6+2+(-6) = -10\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Answer: -10 \n" ); document.write( " \n" ); document.write( " |