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![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Dec 2006 21:01:35 IST
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can anyone solv this sum for me?? find equation of circle whoose centre lies in first qudrant, radius =4,given that it touches the x axis and line 4x-3y=0
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Dec 2006 21:32:57 IST
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let the centre be (-g,-f). 4x=3y touches the circle. So, perpendicular distance from centre to 4x-3y=0 is 4, right. So u get (-4g+3f)/5=4. The second equation is, r^2=g^2 + f^2 -c. Third equation comes from the perpendicular distance from the centre to the line x=0(circle touches x axis). So u have 3 equations and 3 unknowns i.e. g,f & c. So, u can find the equation of the circle.
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Saket Mohan |
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Dec 2006 21:46:47 IST
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its radius is 4 and it touches the x axis ,so the centre become(x,4)
and further using the perpendicular distance from centre to line
will be 4 .therefore directly leading to answer (8,4) making use that
C lies in first quadrant.
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Dec 2006 23:06:26 IST
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kusum i think uve got the question wrong
the circum ference of the circle touches the xaxis not the centre
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Dec 2006 23:56:18 IST
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hiiiiiiiii let the centre be (h,k) since it touches x axis, k = radius=4 equation of circle is (x-h)2+(y-4)2=42 distance from centre to the line 4x-3y=0 is 4 using this you can find h. put h in the eqn of circle and you'll get the answer
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rashmi jain
IITJEE ALL INDIA RANK - 66
doing B.Tech in computer science and engineering from IIT DELHI |
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 25 Dec 2006 08:52:48 IST
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actually john you have misunderstood my soln where you havent read that i marked the centre of circle as (x,4) and not(4,0).you may draw a rough diagram which make the prob even simpler.I hope you have understood what i am trying to tell.AND please dont point out anybody mistake unless you are sure.i hope you change the review on my soln. I hope what Rashmi didi and i did are the same.Infact i explained the entire logic behind it.I would like u to comment on it. thanx
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