why are isocost straight lines
4. Why are isocost lines straight lines? The isocost line represents all possible combinations of labor and capital that may be purchased for a given total cost. The slope of the isocost line is the ratio of the input prices of labor and capital. If input prices are fixed, then the ratio of these prices is clearly fixed and the isocost line is straight. Only when the ratio or factor prices change as the quantities of inputs change is the isocost line not straight. 5.