试题详情

已知两正弦量,U<SUB>1</SUB>=20sin(ωt+π/6),U<SUB>2</SUB>=40sin(ωt-π/3),则U<SUB>1</SUB>比U<SUB>2</SUB>(____)。

A超前30°

B滞后30°

C滞后90°

D超前90°