Question: Q: Rear glass was broken .can I repair it by using warranty

The rear glass can't be repaired and accidental damage is not covered by the standard warranty.

You'll have to buy a replacement.

Unfortunately that's a no, Apple does not fix broken back panels they offer replacement at a cost. You can however will have to go to 3rd Party Repair Shop (Non-AASP repair shop) who can assist with this.

MrPRTR wrote:

Unfortunately that's a no, Apple does not fix broken back panels they offer replacement at a cost. You can however will have to go to 3rd Party Repair Shop (Non-AASP repair shop) who can assist with this.

Which will void the remainder of the phone’s warranty.