If I1=∫π0xsinxecos4xdx&I2=∫π20cosxecos4xdx, then the value of [I1I2] is (where [.] denotes the greatest integer function)
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Solution
I1=∫π0xsinxecos4xdx⋯ (i) I1=∫π0(π−x)sinxecos4xdx⋯ (ii)
On adding (i) and (ii), we get- 2I1=π∫π0sinx.ecos4xdx2I1=2π∫π20sinxecos4xdxI1=π∫π20sinx.ecos4xdxI1=π∫π20cosx.ecos4xdxI1I2=π⇒[I1I2]=3