I read a lecture about Bitcoin Blockchain. As shown in the slide below, a user Alice sends a transaction to BoB. Alice should
1-) Hash(Hash of the transaction of the coin || Bob Public Key || Alice address)
2-) Sign the hash
3-) Send the signed transaction and Alice public key.
My Question: Assuming this is accurate explanation of transation in bitcoin, why the user should hash the transaction before he send it? Also, How a miner can verify the transaction using the public key and the signed transaction? I guess a miner need the original transaction as well as the hash of the transaction.