Asked by  | 25th Oct, 2009, 03:02: PM

Expert Answer:

Equation of family of circles is x2+y2 =r2  

For  line y = x+1 to cut the circles in distinct points roots of the equation obtained by solving them simultaneously

so x2+x2+1+2x = r2

so 2x2+2x+1-r2=0

For the equation to have distinct roots D>0



or r2>1/2

or r >.707

Now a+d =1 and a >.707

so d will be in interval (0,1/4) but   b) (0,122) c) (0,224) are supersets of a so check this question

Answered by  | 11th Dec, 2017, 01:01: PM

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