The first card we have chosen is the Four of Wands. This card represents solidity and stability in relationships, indicating that you have a solid foundation upon which you can build a relationship with this new work friend. The presence of this card suggests that even if you don't know him well, you have the possibility to create something lasting and meaningful together with him.
The second card is the reversed Eight of Pentacles. This card represents the difficulty in establishing a long-term relationship, as it expresses uncertainty and doubts. The fact that it's inside out means that you'll have to overcome these hurdles before you can build a lasting bond with this new work buddy of yours.
The last card is the Ten of Swords. This card speaks of the perseverance and strength needed to achieve one's goals. The fact that it's straight means that you have all the tools to build a solid and lasting relationship with this new work friend of yours.
In conclusion, the three cards suggest that you can trust your new work friend, but you must be prepared to face any difficulties in the course of your relationship. You must also be determined to work hard and persevere to achieve your goals. The answer to the question is therefore: Yes, you can trust your new work friend.