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Find the equation of the circle with centre (1,2) and touching the line 4x-3y+12=0 .

Sagot :

Answer:

The circle will have the form

(x−2)2+(y−3)2=r2

Where r is the distant of the line to the center point.

The distance of the line ax+by+c=0 and the point (px,py) is |apx+bpy+c|a2+b2√ . Plugin in we find the distance to be 3 .

And we have the circle (x−2)2+(y−3)2=9 .

And we solve the equation system given by the circle and the line we find the tangens point on the circle and line is (−25,65) (I have done this with Wolfram Alpha but if you want to do it manually transform the line to either x or y (f.e. x=12−3y4 ) plug it into the circle, solve the resulting quadtric equation ( (−32−3y4)2+(y−3)2=9 (you could solve it by transforming (expanding, simplefying and so on) and using the quadratic formula)))

Step-by-step explanation:

I hope its right