Examine if Rolle.s theorem is applicable to the following functions :
(i) `f(x)=|x|"on"[-1,1]`
(ii) `f(x)=[x]"on"[-1,1]`
(iii) `f(x)=sinx"on"[0,pi]`
(iv) `f(x)=cotx"on"[0,pi]`