若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值?
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若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值?
若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值
若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值?
若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值若tanA=-3/4,求2sin²A+sinAcosA-3cos²A的值?
4sinA=-3cosA ,16sin²A=9cos²A
sin²A=9/25
2sin²A+sinAcosA-3cos²A
=2sin²A-4/3sin²A-3+3sin²A
=11/3sin²A=11/3*9/25=33/25