Use phytagorean theorem to solve the problem.
l² = Δx² + Δy²
Δ means change. Δx means the change of x, and Δy means the change of y.
l² = (x₂ - x₁)² + (y₂ - y₁)²
l² = (5 - (-3))² + (4 - 4)²
l² = (5 + 3)² + 0
l² = 8²
l = 8
The length of the segment is 8