what is the answer for q.no12.

one or more answer may be correct

Do not cancel the term from both side and take sinx=t and after solving u will get the equation as t^5-t^3-t^2+1=0 and we can write it as (t^2-1)(t^3-1)=0 and from this we get two value of t as 1,-1 1 is not considerable because as.we.put 1 in original equation then both side approaches to infinity., That`s why t=-1 is the final answer.