document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=122053>Question 122053</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0582842379/algebrahomeworkh>AS core for edexcel, advanced maths.</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> Hey :D\r<BR>\n" );
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document.write( "i attemped this geometry based homework 2 weeks ago, i managed to do questions 1,2,3,4,5,6, \r<BR>\n" );
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document.write( "which i found challenging as circles arent my strong point :D i tried for twice to do questions 7,8,9.\r<BR>\n" );
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document.write( "With no luck, it has driven me actually crazy, ive tried so hard, and when i got it back earlier today he said, try again.\r<BR>\n" );
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document.write( "So i would really appreciate if someone could help me on these 3 questions, i have a headache from them now, i just wanna know how to do them :(\r<BR>\n" );
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document.write( "7.<BR>\n" );
document.write( "Find the equation of the circle whose centre is (3, -5) and which passes through the point (6, -7).\r<BR>\n" );
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document.write( "( i thought i was really getting somewhere with this question, i think just a small thing i must have done wrong somewhere).\r<BR>\n" );
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document.write( "8.<BR>\n" );
document.write( "The points (10, -4) and (2,2) are the ends of a diameter of a circle, find the equation of the circle?\r<BR>\n" );
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document.write( "I went along the lines of finding the radius by halving... etc, again, something i think only small occured wrong.\r<BR>\n" );
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document.write( "9. ( this i cant do at all)\r<BR>\n" );
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document.write( "they give 3 points on a circle and must find the equation from only 3 points in a circle.\r<BR>\n" );
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document.write( "I have NO idea in the world how to do this, please help :D\r<BR>\n" );
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document.write( "a circle passes through the points (6,3), (-5,2) and (7,2) , find the equation of the circle.\r<BR>\n" );
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document.write( "Thank you SO much for anyhelp, im sorry for asking so much, but ive tried 2 days, tried really hard to understand it, read textbooks and internet pages :( Im sorry but i really need help thanks you SO much!  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #89610 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=89610\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the general equation for a circle is (x-h)^2+(y-k)^2=r^2 __ (h,k) is the center, r is the radius\r<BR>\n" );
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document.write( "7.  the radius is the distance between the center and any point on the circle<BR>\n" );
document.write( "__ using the distance formula, r^2=(-7-(-5))^2+(6-3)^2 __ r^2=13<BR>\n" );
document.write( "__ so the equation is (x-3)^2+(y+5)^2=13\r<BR>\n" );
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document.write( "8.  the center is the midpoint of the diameter __ ((10+2)/2,(-4+2)/2) __ (6,-1)<BR>\n" );
document.write( "__ using the distance formula, r^2=(10-6)^2+(-4-(-1))^2 __ r^2=25<BR>\n" );
document.write( "__ so the equation is (x-6)^2+(y+1)^2=25\r<BR>\n" );
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document.write( "9.  the second and third points have the same y-coordinate, so a line connecting them is horizontal<BR>\n" );
document.write( "__ the midpoint of the line has the same x-coordinate as the center of the circle __ (-5+7)/2=1, so the center is (1,y)\r<BR>\n" );
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document.write( "all radii of a circle are equal, so (distance formula again) __ (1-6)^2+(y-3)^2=(1-7)^2+(y-2)^2<BR>\n" );
document.write( "__ 25+y^2-6y+9=36+y^2-4y+4 __ -2y=6 __ y=-3<BR>\n" );
document.write( "__ using the distance formula, r^2=(1-(-5))^2+(-3-2)^2 __ r^2=61<BR>\n" );
document.write( "__ so the equation is (x-1)^2+(y+3)^2=61 </SPAN>\n" );
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