If x=a sec θ+b tan θ and y=a tan θ+b sec θ, then x2−y2a2−b2= ___
tan[sec−1√1+x2]=
If (tan x +sec x)(tan y + sec y)(tanz +sec z) = (sec x - tan x )(sec y - tan y ) (secz - tan z) = K, then the value of K is