According to this approach the firm is in Equilibrium position at the quantity where the difference between TR & TC is maximum.
At Point B & E the difference between TR & TC is maximum and firms in Equilibrium position.
At this point profit is maximum
MR = MC
2. MR , MC Approach:-
According to this approach the firm is in Equilibrium position where the MC and MR of firm are equal, and at that point profit is maximum.
Where MC = MR at that quantity the price can be determined by firm itself and at that point average revenue decides the price of the product.
=>> In Monopoly firm is a price setter under MR , MC approach.