∫(0~π/4)x*sinxdx
=- ∫(0~π/4)xdcosx
=-xcosx (0~π/4)xdcosx+ ∫(0~π/4)cosxdx
=(-xcosx+sinx)(0~π/4)
=(-π/4*√2/2+√2/2)-(0+0)
=√2(4-π)/8
∫(0~π/4)x*sinxdx
=- ∫(0~π/4)xdcosx
=-xcosx (0~π/4)xdcosx+ ∫(0~π/4)cosxdx
=(-xcosx+sinx)(0~π/4)
=(-π/4*√2/2+√2/2)-(0+0)
=√2(4-π)/8