If sin theta=3/5, then csc theta=​

You would use any explicit rule to find this:
f(n)= f(1)+(n-1)d 
     
      f(1) is the first term of the sequence
      r  is the common difference

f(n)= -3+(n-1)×2
f(11)= -3+(11-1)×2         n=11 since you want the 11th term
f(11)= -3+(10)×2
f(11)= -3+20
f(11)= 17

the 11th term of the sequence is 17