The optimal viewing distance for a 43-inch LED TV depends on the resolution of the TV and your personal preferences. As a general rule of thumb, the recommended viewing distance for a 43-inch TV is around 4 to 7 feet (1.2 to 2.1 meters).
If your TV has a 1080p resolution, the ideal viewing distance is about 6 to 7 feet (1.8 to 2.1 meters) away from the screen. However, if your TV has a 4K resolution, you can sit a bit closer, around 4 to 5 feet (1.2 to 1.5 meters), to fully appreciate the enhanced picture quality.
Ultimately, the best viewing distance for you will depend on your personal preference, the size and layout of your room, and the quality of the TV's picture. It's a good idea to experiment with different viewing distances until you find the one that feels most comfortable and enjoyable for you.