若π/4

若π/4理由 若3π/4 若π/4 若π/4 若π/4 若π/4 若π/4 若π/4 若π/4 若π/4 若π/4 若sinx>cosx 如何得出 2kπ+π/4 若sinX/cosX=4/3(π 一道数学题,感激不尽!若π/4 已知sin(a+π/4)sin(a-π/4)=1/3,若π/2 若x属于（π/2,π）,3cos2x=sin(π/4-x),则sin2x 若π 若π