Question

Given ∠3≅∠4

Which of the following statements cannot be proved
∠1≅∠2
∠F≅∠2
∠1+∠4≅∠2+∠3
∠1+∠2≅∠3+∠4

Answer 1

∠1+∠2≅∠3+∠4 cant be proven because sum of two obtuse angles is sure to be greater than sum of two acute angles of a triangle.