An analyst at a company notes that its cost of debt is far below that of equity. He concludes that it is important for the firm to maintain the ability to increase its borrowing because if it cannot borrow, it will be forced to use more expensive equity to finance some projects. This might lead it to reject some projects that would have seemed attractive if evaluated at the lower cost of debt.

How do you balance the amount of equity and debt? Explain the significance of maintaining the ability to increase borrowing capacity for a company with a lower cost of debt compared to equity. How does this impact project evaluation and investment decisions, and what role does the concept of cost of capital play in such considerations?