Sentence:  Just as the pressure exerted by surface tension in a spherical drop is * * f and the pressure exerted by surface tension on a cylindrical shape is * * f , the pressure exerted by any curved surface is * * f , where |g is the interfacial tension and * * f and * * f are the two <WSD>radii</WSD> of curvature . 
Meaning of the word marked with <WSD> tags:  the radius of the circle of curvature; the absolute value of the reciprocal of the curvature of a curve at a given point