Final answer:
The line connecting the points of tangency between successive isoquants and iso-cost lines is known as the firm's expansion path.
Step-by-step explanation:
The line connecting the points of tangency between successive isoquants and iso-cost lines is known as the firm's expansion path. This path represents the various combinations of inputs that the firm can use to produce a given level of output while minimizing costs. It shows how the firm can expand production by adjusting the quantities of inputs in response to changes in output and input prices.