Frist consider the circuit of Fig. 4.1, which was analyzed in the previous section. The circuit variable i1 and i2 were found in (4.5). Let us now use superposition to find these responses. First we kill the current source, resulting in the modified circuit of Fig. 4.3(a), and determine i1^a and i2^a. This is the component a problem, and i1^a and i2^a are the components of the responses i1 and i2 due to source a (the voltage source). This is a single-loop circuit, and