proposition: Theorem slope_lt_1312_2313 : ∀ pt₁ pt₂ pt₃, fst pt₁ < fst pt₂ < fst pt₃ → slope_expr pt₁ pt₃ < slope_expr pt₁ pt₂ → slope_expr pt₂ pt₃ < slope_expr pt₁ pt₃.
proof: Proof. intros (x₁, y₁) (x₂, y₂) (x₃, y₃) Hlt H. rewrite Qlt_alt in H |- *; rewrite <- H. symmetry; apply slope_cmp₂; assumption. Qed.
imports: Utf8 QArith Slope_base Misc