What is the condition on a,b,ca, b, ca,b,c for the lines ax+by+c=0ax+by+c=0ax+by+c=0, bx+cy+a=0bx+cy+a=0bx+cy+a=0, and cx+ay+b=0cx+ay+b=0cx+ay+b=0 to be concurrent?
a+b+c=0a+b+c = 0a+b+c=0 or a=b=ca=b=ca=b=c
a2+b2+c2=ab+bc+caa^2+b^2+c^2 = ab+bc+caa2+b2+c2=ab+bc+ca
abc=1abc = 1abc=1
a+b+c=1a+b+c = 1a+b+c=1