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Question 331802:  What is the equation of a circle touching the lines x-3y-11=0 and 3x-y-9=0 and having its center on the line x+2y+19=0. 
 Answer by Alan3354(69443)      (Show Source): 
You can  put this solution on YOUR website! What is the equation of a circle touching the lines x-3y-11=0 and 3x-y-9=0 and having its center on the line x+2y+19=0. 
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Find the bisector of the two tangent lines, x-3y-11=0 and 3x-y-9=0. 
To do that, find the intersection of the 2 lines. 
The slope of the bisector is tan(arctan(1 line) + arctan(other line)) 
The slope = 1 
With the slope and the point of intersection, find the equation of the bisector. 
Then find the intersection of the bisector and the line x+2y+19 = 0.  That's the center of the circle. 
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Find the distance from the center to either x-3y-11=0 or 3x-y-9=0, that's the radius. 
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email for any assistance needed at moralloophole@aol.com 
 
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