If x∈(7π,8π), then tan−11−cosx1+cosx=
-x2
x2
4π−x2
none of these
tan−11−cosx1+cosx=tan−1−tanx2 =tan−1tan4π−x2=4π−x2∵7π<x<8π⇒7π2<x2<4π,sotanx2<0