tan18°=多少(要分数几分之根号几的)

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tan18°=多少(要分数几分之根号几的)

tan18°=多少(要分数几分之根号几的)
tan18°=多少(要分数几分之根号几的)

tan18°=多少(要分数几分之根号几的)
sin3*18=3sin18-4sin^318
cos36=1-2sin^218
sin54=cos36
3sin18-4sin^318=1-2sin^218
4sin^318-2sin^218-3sin18+1=0
(sin18-1)(4sin^218+2sin18-1)=0
sin18=(√5-1)/4
cos18=√(10+2√5)/4
tan18=(√5-1)/√(10+2√5)