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What should we do for the poverty areas?

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What should we do to become dream chasers?

若正弦量u的相位超前电流i200°,就应该说电流滞后电压u160°,此时Φ=()

A. 160°
B. -160°

i=i1+i2+i3=4√2sinωtA+8√2sin(ωt+90°)A+4√2sin(ωt-90°)A,则总电流I的相量表示式为( )

A. I=4√2∠45°A
B. I=4√2∠-45°A
C. I=4∠45°A

U=(∠30°+∠-30°+2√3∠180°)V,则总电压U的三角函数式为()

A. u=√3sin(ωt+π)V
B. u=-√6sinωtV
C. u=√3√2sinωtV