question_answer

Two given circles \[{{x}^{2}}+{{y}^{2}}+ax+by+c=0\]and \[{{x}^{2}}+{{y}^{2}}+dx+ey+f=0\]will intersect each other orthogonally, only when                   

A)            \[a+b+c=d+e+f\]                 

B)            \[ad+be=c+f\]

C)            \[ad+be=2c+2f\]                   

D)            \[2ad+2be=c+f\]