Young cos θ at (γ_sv, γ_sl, γ_lv) = (1, 0, 1): cos θ = 1 ⇒ θ = 0 (full wet)

Sympy-exact witness of the Young-equation full-wetting limit. Setup: γ_sv=1, γ_sl=0, γ_lv=1 gives cos θ = 1 exactly, θ = 0 (complete wetting). Physical picture: a solid with surface energy equal to the liquid-vapour surface tension, and…