Two circles of radii `r_(1)` and `r_(2), r_(1) gt r_(2) ge2` touch each other externally. If `theta` be the angle between the direct common tangents, then,
A. `theta = sin ^(-1) ((r_(1)+r_(2))/(r_(1)-r_(2)))`
B. `theta = 2 sin^(-1) ((r_(1)-r_(2))/(r_(1)+r_(2)))`
C. `theta=sin^(-1)((r_(1)-r_(2))/(r_(1)+r_(2)))`
D. none of these