If inside a big circle exactly `n(nlt=3)` small circles, each of radius `r ,` can be drawn in such a way that each small circle touches the big circle and also touches both its adjacent small circles, then the radius of big circle is (a) `r(1+cos e cpi/n)` (b) `((1+tanpi/n)/(cospi/pi))` (c) `r[1+cos e c(2pi)/n]` (d) `(r[s inpi/(2n)+cos(2pi)/n]^2)/(sinpi/n)`

Options

A. `r(1+ cosec (pi)/(n))`
B. `((1+tan""(pi)/(n ))/(cos ""(pi)/(n )))`
C. `r[1+cosec (2pi)/(n)]`
D. `(r [sin ""(pi)/(2n)+ cos ""(2pi)/(n)]^(2))/(sin "'(pi)/(n))`

Answer

A, D