已知α为锐角,且sin^2α+sinαcosα-2cos^2=0.(1)求tanα的值.(2)求sin[α-(π/3)]
人气:199 ℃ 时间:2020-03-25 00:38:11
解答
(1)
sin^2α+sinαcosα-2cos^2=0
(sinα+2cosα)(sinα-cosα)=0
因为α为锐角
所以
sinα=cosα
tanα=1
所以
α=π/4
(2)
sin(α-π/3)
=sinαcosπ/3-cosαsinπ/3
=√2/2*1/2-√2/2*√3/2
=(√2-√6)/4
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