The graph of the total revenue of a demand curve which is a strait line, with price on the y axis and quantity on the x axis has the shape of a parabola opening downward. It starts at zero revenue, when quantity is zero and ends at zero revenue when price is zero. | The graph of the total revenue of a demand curve which is a strait line, with price on the y axis and quantity on the x axis has the shape of a parabola opening downward. It starts at zero revenue, when quantity is zero and ends at zero revenue when price is zero. |