limt→0(11sin2t+21sin2t+⋯+n1sin2t)sin2t is equal to [2023]
(3)
Let L=limt→0(11sin2t+21sin2t+…+n1sin2t)sin2t
⇒L=limt→0n[(1n)cosec2t+(2n)cosec2t+ …+(n-1n)cosec2t+1]sin2t
⇒L=n(1sin(0))=n(1)=n[0<kn<1,(kn)∞=0 for 1≤k<n]