∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C]
  [inst_2 : CategoryTheory.HasShift C ℤ] (T : CategoryTheory.Pretriangulated.Triangle C),
  CategoryTheory.CategoryStruct.comp
      (((CategoryTheory.Pretriangulated.invRotate C).comp (CategoryTheory.Pretriangulated.rotate C)).obj T).mor₁
      (CategoryTheory.Iso.refl
          (((CategoryTheory.Pretriangulated.invRotate C).comp (CategoryTheory.Pretriangulated.rotate C)).obj
              T).obj₂).hom =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Iso.refl
          (((CategoryTheory.Pretriangulated.invRotate C).comp (CategoryTheory.Pretriangulated.rotate C)).obj
              T).obj₁).hom
      ((CategoryTheory.Functor.id (CategoryTheory.Pretriangulated.Triangle C)).obj T).mor₁