Let S1 and S2 be two unit circles with centres at C1(0,0) and C2(1,0) respectively. Let S3 be another circle of unit radius, passing through C1 and C2 and its centre is above the x-axis. If equation of common tangent to S1 and S3, which does not pass through S2, is ax+by+2=0, then the value of a2−b is

Let S1 and S2 be two unit circles with centres at C1(0,0) and C2(1,0)

1.	Let S1 and S2 be two unit circles with centres at C1(0,0) and C2(1,0) respectively. Let S3 be another circle of unit radius, passing through C1 and C2 and its centre is above the x-axis. If equation of common tangent to S1 and S3, which does not pass through S2, is ax+by+2=0, then the value of a2−b is
Answer» Let $S_{1}$ and $S_{2}$ be two unit circles with centres at $C_{1} (0, 0)$ and $C_{2} (1, 0)$ respectively. Let $S_{3}$ be another circle of unit radius, passing through $C_{1}$ and $C_{2}$ and its centre is above the $x$ -axis. If equation of common tangent to $S_{1}$ and $S_{3}$ , which does not pass through $S_{2}$ , is $a x + b y + 2 = 0$ , then the value of $a^{2} - b$ is