In the short run,the competitive firm maximizes its profit by choosing an output q*at which its marginal cost MC is equal to the price P(or marginal revenue MR)of its product. The profit of the firm is measured by the rectangle ABCD. In the short run, the competitive firm maximizes its profit by choosing an output q* at which its marginal cost MC is equal to the price P (or marginal revenue MR) of its product. The profit of the firm is measured by the rectangle ABCD