单项选择题
A.5sin(ωt-36.9°) B.5sin(ωt-53.1°) C.-5sin(ωt+53.1°) D.-5sin(ωt-36.9°)
A.32e-2t+21e-3t) B.8e-2t+9e-3t) C.-32e-2t-21e-3t) D.-8e-2t-9e-3t)
A.1-)B.4(1-)C.9(1-)D.36(1-)