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Find the center of the smallest circle which cuts circles `x^2+y^2=1`and `x^2+y^2+8x+8y-33=0`orthogonally. |
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Answer» Let the equation of the required circle be `x^(2)+y^(2)+2gx+2fy+c=0`. This circle cuts the given two circles othogonally. `:. 2g(0)+2f(0)= -1+c,` `:. c=1` and `2(g)(4)+2(f)(4)= -33+c= -32` `:. G+f= -4` `:. `Radius of the circle `sqrt(g^(2)+f^(2)-c)` `=sqrt(g^(2)+(g+4)^(2)-1) ` `=sqrt(2g^(2)+8g+15)` `=sqrt(2(g+2)^(2)+7)` Radius is minimum if `g+2=0` or `g =-2`. `:. f= -1` Hence, equation of the circle is `x^(2)+y^(2)-4x-4y+1=0`. |
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