(1)由csinA= 3 acosC,结合正弦定理得, a sinA = c 3 cosC = c sinC ,∴sinC= 3 cosC,即tanC= 3 ,∵0<C<π,∴C= π 3 ;(2)由(1)知B= 2π 3 -A,∴ 3 sinA-sin(B+ π 2 )= 3 sinA-cosB= 3 sinA-cos(