The value of  tan-1(1) + cos-1(-1/2) + sin-1(-1/2) is equal to-

π/4 -π/4 3π/4 -3π/4

3π/4

Let  tan-1 (1) = x. Then, tan x =1 = tan (π/4)  so cos-1 (1) = (π/4) Let, cos-1(-1/2) = y. Then cos y = -1/2= cos(π/3) = cos(π-π/3)= cos(π/3) so cos-1 (-1/2) = (2π/3) Let, sin-1(-1/2) = z. Then sin z = -1/2= -sin(π/6) = sin(-π/6) so sin-1 (-1/2) = (π/6) so, tan-1(1) + sin-1(-1/2)+ cos-1(-1/2)   = π/4+ π/2 = 3π/4