Two soap bubbles of radius `r_(1)` and `r_(2)` combine. Find radius of curvature of the common surface separating them.

Explanation

`P_(0) + (4T)/(r_(2)) - (4T)/(r_(c)) - (4T)/(r_(1)) = P_(0)`
`(1)/(r_(c)) = (1)/(r_(2)) - (1)/(r_(1))`
`r_(c) = (r_(1)r_(2))/(r_(1) - r_(2))`