Why are there two isocost lines? and why are we drawing a lot of the isoquant lines? please explain it step by step, thanks !

A rm nds that no matter how much output it produces and no matter how input prices vary, it always minimizes its costs by buying half as many units of capital as of labour. Draw this rm's isoquant map. ANSWER: If K and L are perfect complements, the two inputs will be used in fixed proportion, no matter what the slope of the isocost line. In the graph below solid lines are isoquants and dashed lines are isocosts. K