已知sinα-3cosα=0,求sin²α+sinαcosα+2的值是
人气:205 ℃ 时间:2020-03-19 20:00:23
解答
sin²α+sinαcosα+2
=(sin²α+sinαcosα)/(sin²α+cos²α)+2
代入sinα-3cosα=0,即sinα=3cosα
=(9cos²α+3cos²α)/(9cos²α+cos²α)+2
=12/10+2
=6/5+2
=16/5
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