Answer: Yes, there can be a triangle with the side lengths 10.5 cm, 8.0 cm, and 4.0 cm.
Explanation:
We know that triangle inequality says that the sum of any two side of a triangle must be greater to the third side of the triangle.
To check 10.5 cm, 8.0 cm, and 4.0 cm be the side lengths of a triangle, we should check the triangle inequality as.

Thus, the given side lengths satisfy the triangle inequality.
Hence, there can be a triangle with the side lengths 10.5 cm, 8.0 cm, and 4.0 cm.