Question

Principal value of tan^ -1 1 +cos^-1 (-1/2) +sin^-1(-1/2) is equal to (a)2π/3 (b)3π/4 (c)π/2 (d) 6π

Answer 1

$= \tan(1)$
=tan^-1(1)+cos^-1(-1/2)+sin^-1(-1/2)
=π/4+2π/3-π/6
=π(1/4+2/3-1/6)
=π(3+8-2)/12
=(9/12)π
=3π/4