设f(x)=6cos平方x-根号3sin2x若锐角α满足f(α)=3-2根号3,求tan4/5α的值
人气:362 ℃ 时间:2020-02-01 05:50:31
解答
f(a)=6cos²a-√3sin2a
=3(1+cos2a)-√3sin2a
=3cos2a-√3sin2a+3
=2√3(√3/2cos2a-1/2sin2)+3
=2√3cos(2a+π/6)+3
根据题意
2√3cos(2a+π/6)+3=3-2√3
cos(2a+π/6)=-1
0
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