已知tanα=3,求2(sinα)^2-3cosαcosα的值_数学解答

已知tanα=3,求2(sinα)^2-3cosαcosα的值

人气：118 ℃　时间：2020-02-01 08:10:29

解答

2(sinα)^2-3cosαcosα
=[2(sinα)^2-3cosαcosα]/((sinα)^2+(cosα)^2
=2(tanα)^2-3/ [(tanα)^2+1]
=2*3^2-3/(3^2+1)
=3/2