Find the biceps and triceps brachii. are they antagonists or synergists?

According to their function, muscle groups are divided into antagonists and synergists. The antagonist muscles take part in opposite movements of the joint and contract alternately, while the synergistic muscles, on the contrary, help each other in the implementation of one movement and act simultaneously.
The biceps brachii or biceps is the flexor of the elbow joint, and the triceps or triceps is the extensor of the elbow. They act by alternately bending and unbending our arm at the elbow. So these muscles are antagonists.