送交者: 短江学者 于 2010-12-18, 22:37:30:
回答: 唱罢,洗耳恭听。 由 潜伏九号 于 2010-12-18, 22:21:29:
sin(w+d)+sin(w-c)= 2sin[w+0.5(d-c)]cos[0.5(d-c)].
since d-c is very small so this is approximately 2sin(w). This says that if several bad singers are not all bad in the same direction they can correct each other. One can see this in high school performance :)