In the accompanying diagram, the linear total revenue curve represents the case in which the firm is a perfect competitor in the goods market, and thus cannot set its own selling price. The profit-maximizing output level is represented as the one at which total revenue is the height of \text{C} and total cost is the height of \text{B}; the maximal profit is measured as the length of the segment \overline{\text{CB}}. This output level is also the one at which the total profit curve is at its maximum.
