Using the auxiliary hypothesis metatheorem prove ⊢ (∃x)A → (∃x) ( A ∧ (A ∨ B) )

Please use the graphical technique. 

Here is an example of it:

  • The auxiliary hypothesis is: "Suppose that Γ ⊢ (∃x)A."

  • I don't understand the technique. Can you give a definition rather than an example?

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