Chromecast? How do you think that world work?
You need a bluetooth transmitter for the TV if it doesn't have one built-in, similar to this:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Plug it into the TV's headphone jack or use adapter cables if required for the TV's Line Out.
Then pair it with the radio's Bluetooth Receiver to get the TV sound to the radio.