3[sin4(3π2−α)+sin4(3π+α)]−2[sin6(π2+α)+sin6(5π−α)]=
3
3{sin4(3π2−α)+sin4(3π+α)}−2{sin6(π2+α)+sin6(5π−α)}=3{(−cos α)4+(−sin α)4}−2{cos6 α+sin6 α}=3{(cos2 α+sin2 α)2−2 sin2 αcos2 α }−2{(cos2 α+sin2 α)3−3 cos2 α sin2 α(cos2 α+sin2 α)}=3−6 sin2 α cos2 α−2+6 sin2 α cos2 α=3−2=1
Trick : Put α=0, π2, the value of expression remains 1 i.e., it is independent of α.