Let `h` be the height, `l` the slant height and `r_1` and `r_2` the radii of the ends `(r_1 > r_2 )` of the frustum of a cone then slant height of frustum of cone is given by

Options

A. `sqrt(h^2+r_1^2- r_2^2)`
B. `sqrt(h^2+r_1^2+ r_2^2)`
C. `sqrt(h^2+(r_1 - r_2)^2)`
D. `sqrt(h^2-(r_1 - r_2)^2)`

Answer

C