The ∫sin2xcos6xdx is a
is a polynomial of degree 5 in sinx
is a polynomial of degree 4 in tanx
is a polynomial of degree 5 in tanx
is a polynomial of degree 5 in cosx
Putting tanx=t the given integral can be written as
∫t21+t2dt=t33+t55+C=tan5x5+tan3x3+C
which is a polynomial of degree 5 in tan x