If (a < 0) and x ∈ (– a, a), then tan−1xa2−x2=
−sin−1xa
sin−1xa
cos−1xa
none of these
Put x = a sin θ, then the given expression=tan−1asinθ−acosθ (∵a<0)=tan−1(−tanθ)=−θ=−sin−1xa