已知sin（α-3π）+cos(π/2+α)=m,求cos（α-7π/2）+2sin（2kπ-α）的值

显示全部楼层 · 2012-4-3 12:40:26

sin（α-3π）+cos(π/2+α)=m,-sinα-sinα=m所以：sinα=-m/2cos（α-7π/2）+2sin（2kπ-α）=-sinα-2sinα=-3sinα=3m/2...

千问 · 2012-4-3 12:40:26

∵sin（α-3π）+cos(π/2+α)=m,∴-sinα-sinα=m∴sinα=-m/2∴cos（α-7π/2）+2sin（2kπ-α）=cos(π/2+α)-2sinα=-3sinα=3m/2...

千问 · 2012-4-3 12:40:26

sin(α-3π)+cos(π/2+α)=-sinα-sinα=-2sinα=msinα=-m/2cos(α-7π/2)+2sin(2kπ-α)=-sinα-2sinα=-3sinα=3m/2...

千问 · 2012-4-3 12:40:26

sin（α-3π）+cos(π/2+α)=m-sinα-sinα=msinα=-m/2原式=sinα-2sinα=-sinα=m/2...