Explanation:
C \(: \mathrm{x}^2+\mathrm{y}^2-6 \mathrm{x}-8 \mathrm{y}+9=0\)
\(2 \mathrm{~g}=-6, \quad 2 \mathrm{f}=-8\)
\(\mathrm{~g}=-3, \quad \mathrm{f}=-4\)
\((-\mathrm{g},-\mathrm{f})=(3,4)\)
\(\mathrm{x}^2+\mathrm{y}^2=1\)
\(\text { Centre, } \mathrm{C}_2(0,0), \mathrm{R}_2=1\)
\(\therefore \mathrm{R}_1+\mathrm{R}_2=4+1=5\)
\(\therefore \mathrm{C}_1 \mathrm{C}_2=\mathrm{R}_1+\mathrm{R}_2\)
In this case two direct tangent are real and distinct while the transverse tangents are coincident.
So, number of common tangents \(=3\)
In this case two direct tangent are real and distinct while the transverse tangents are coincident.
So, number of common tangents \(=3\).