已知tana=3 ,求(sin²a+sinacosa-3cos²a/(sin²a+3cos²a)求过程请问为什么要同除以Cos²?
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/02 21:36:12
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已知tana=3 ,求(sin²a+sinacosa-3cos²a/(sin²a+3cos²a)求过程请问为什么要同除以Cos²?
已知tana=3 ,求(sin²a+sinacosa-3cos²a/(sin²a+3cos²a)求过程
请问为什么要同除以Cos²?
已知tana=3 ,求(sin²a+sinacosa-3cos²a/(sin²a+3cos²a)求过程请问为什么要同除以Cos²?
同除以Cos²a
才能使分子分母上面都变成了tana啊
(sin²a+sinacosa-3cos²a/(sin²a+3cos²a)
=(tan²a+tana-3)/(tan²a+3)
=(9+3-3)/(9+3)
=9/12
=3/4