We use the tomographic density of states (TDOS), which is a measure of the density of states for a single slice through the band structure of a solid, to study the temperature evolution of the superconducting gap in the cuprates. The TDOS provides accuracy in determining both the superconducting pair-forming strength Δ and the pair-breaking rate Γ. In both optimally and underdoped Bi2Sr2CaCu2O8+δ, we find the near-nodal Δ smoothly evolves through the superconducting transition temperature—clear evidence for the existence of preformed pairs. Additionally, we find the long-observed “filling” of the superconducting gap in the cuprates is due to the strongly temperature-dependent Γ.