The show interface port-channel summary command shows the LAG number (VLT port channel 1 in this example), mode, status, and ports used in the port channel.
Z9432-1# show interface port-channel summary
LAG Mode Status Uptime Ports
10 L2 up 00:04:43 Eth 1/1/9:1 (Up)
Eth 1/1/10:1 (Up)
Z9432-1#