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Ask iit jee aieee pet cbse icse state board experts Expert Question: circles!!!!!!!!!! DOUBT!!
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vigneshiam (75)

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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
    
saketmohan06 (7)

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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.
 

Saket Mohan
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kusum (206)

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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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jhon (5)

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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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rashmi_jain (183)

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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

rashmi jain
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doing B.Tech in computer science and engineering from IIT DELHI
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kusum (206)

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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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