let th be Real; ( Partial_Sums (th P_sin) is convergent & Sum (th P_sin) = Im (Sum ((th * <i>) ExpSeq)) & Partial_Sums (th P_cos) is convergent & Sum (th P_cos) = Re (Sum ((th * <i>) ExpSeq)) )
A1:
Sum ((th * <i>) ExpSeq) = (Sum (Re ((th * <i>) ExpSeq))) + ((Sum (Im ((th * <i>) ExpSeq))) * <i>)
by COMSEQ_3:53;
then A2:
Sum (Re ((th * <i>) ExpSeq)) = Re (Sum ((th * <i>) ExpSeq))
by COMPLEX1:12;
A3:
Sum (Im ((th * <i>) ExpSeq)) = Im (Sum ((th * <i>) ExpSeq))
by A1, COMPLEX1:12;
A4:
( Partial_Sums (Re ((th * <i>) ExpSeq)) is convergent & lim (Partial_Sums (Re ((th * <i>) ExpSeq))) = Re (Sum ((th * <i>) ExpSeq)) )
by A2, SERIES_1:def 2, SERIES_1:def 3;
A5:
( Partial_Sums (Im ((th * <i>) ExpSeq)) is convergent & lim (Partial_Sums (Im ((th * <i>) ExpSeq))) = Im (Sum ((th * <i>) ExpSeq)) )
by A3, SERIES_1:def 2, SERIES_1:def 3;
then
Partial_Sums (th P_cos) is convergent
by SEQ_2:def 6;
then A9:
lim (Partial_Sums (th P_cos)) = Re (Sum ((th * <i>) ExpSeq))
by A6, SEQ_2:def 7;
then
Partial_Sums (th P_sin) is convergent
by SEQ_2:def 6;
then
lim (Partial_Sums (th P_sin)) = Im (Sum ((th * <i>) ExpSeq))
by A10, SEQ_2:def 7;
hence
( Partial_Sums (th P_sin) is convergent & Sum (th P_sin) = Im (Sum ((th * <i>) ExpSeq)) & Partial_Sums (th P_cos) is convergent & Sum (th P_cos) = Re (Sum ((th * <i>) ExpSeq)) )
by A6, A9, A10, SEQ_2:def 6, SERIES_1:def 3; verum