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问题: 请教高一数学题

已知tan(a-c)/tana+sin^b/sin^a=1 求证tan^b=tana*tanc

解答:

sin^b=sin^a[1-tan(a-c)/tana],csc^b=csc^a*tana/[tana-tan(a-c)],
cot^b=[csc^a*tana-tana+tan(a-c)]/[tana-tan(a-c)]
=[cota+tan(a-c)]/[tana-tan(a-c)],
tan^b=tana*[tana-tan(a-c)]/[1+tana*tan(a-c)]
=tana*tanc.