已知cosα-sinα=3√ 2⼀5,且π<α<3π⼀2,求sin2α+2sin^2α⼀1tanα

2025-02-24 17:28:52
推荐回答(2个)
回答1:

cosα-sinα=3√ 2/5
(cosα-sinα)^2 = 18/25
1 -2sinαcosα = 18/25
2sinαcosα = 1 - 8/25 = 7/25

sin2α+2sin^2α/tanα
= 2sinαcosα+2sin^2α/(sinα/cosα)
= 2sinαcosα+2sinαcosα
= 2*sinαcosα
= 2*7/25
= 14/25

回答2:

-28/75