The set of values of a for which x2+ax+sin−1(x2−4x+5)+cos−1(x2−4x+5)=0 has at least one solution is
The value of a=−λ−πμ, such that x2+ax+sin−1(x2−4x+5)+cos−1(x2−4x+5)=0 has atleast one solution. Then λ+μ is equal to