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December 16th, 2009, 11:45 PM  #1 
Newbie Joined: Dec 2009 Posts: 3 Thanks: 0  Find intersection of a Circle with Yaxis...
Please find the equation of circle, C1: x2 + y2 + 4 x  6y  3 = 0 It has centre (2,3) & Radius = 4 Hence, I need to find the intersection of the circle with Yaxis in 2 points A and B Then to find the point D of intersection of the tangent line to the circle @ A and B Thank you in Advance 
December 17th, 2009, 02:29 AM  #2 
Senior Member Joined: Feb 2009 From: Adelaide, Australia Posts: 1,519 Thanks: 3  Re: Find intersection of a Circle with Yaxis... 
December 18th, 2009, 12:51 PM  #3 
Newbie Joined: Dec 2009 Posts: 7 Thanks: 0  Re: Find intersection of a Circle with Yaxis...
In this problem, the intersection with the axis Oy, is found by using itīs equation (Oy): x=0. Solving the system defined by both equations will give you the points A(0,a) and B(0,b), a and b will be the solutions to y26y3=0. At this time, you can also calculate the tangents on both of these points, but their intersection should be at y=3, can you see why? Solving the equation y = (6 +sqr(6*64(3))/2= 3 + sqr48/2= 3 + sqr12 = 3 +2sqr3 Then a = 3+2sqr3 and b = 32sqr3. 

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circle, find, intersection, yaxis 
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