Let S be the sum of all x in the interval [0,2π] such that 3cot2x+8cotx+3=0, then the value of Sπ is
Let f:(−1,1)→R be such that f(cos4θ)=22−sec2θ for θ∈(0,π4)∪(π4π2).Then the value (s) of f(13) is (are)