Just so that we're clear, are you asking to simplify
show that the value of
[{sin^3(pi + theta)}/{cos ^3(pi/2 + theta)}] * [{cos^3(-theta)}/{sin^3(pi- theta)}] * [{tan(2pi-theta)}/{cosec^2theta}] *
[{sec^2 (pi-theta)}/{sin(2pi + theta)}]
is independent of theta
my incomplete soln-
[{sin^3(pi + theta)}/{cos ^3(pi/2 + theta)}]= -sin^3theta / sin^3theta
[{cos^3(-theta)}/{sin^3(pi- theta)}] = cos^3 theta / sin^3 theta