A certain power amplifier with crossover distortion has the input/output voltage relationship vo (t) = vi (t)3 (2.39) a) Use example voltage values to show that this does not satisfy the relationship. b) Let vi (t) = sin (pi t) . Using a triple angle formula, show that the resulting output includes a term that is at the same frequency as the input, and then another term at a higher frequency. What is that higher frequency?