We know that the sum of all the angles in triangle ACE is 180∘.∠ A+∠ C+∠E=180∘ ..(1)We know that the sum of all the angles in triangle BDF is 180∘.∠ B+∠ D+∠F=180∘ ..(2)Now by adding both equations (1) and (2) we get∠ A+∠ C+∠ E+∠ B+∠ D+∠F=180∘ +180∘On further calculation∠ A+∠ B+∠ C+∠ D+∠ E+∠F=360∘Therefore, it is proved that ∠ A+∠ B+∠ C+∠ D+∠E +∠F=360∘.