sinx+siny=根号3 cosx+cosy=2根号3/3 求tanxtany错了，第一个我等于根

sinx+siny=根号3 cosx+cosy=2根号3/3 求tanxtany错了，第一个我等于根

sinx+siny=根号2 (1)cosx+cosy=2根号3/3 (2)(1)平方+(2)平方2+2sinxsiny+2cosxcosy=2+4/3cosxcosy+sinxsiny=2/3 (3)cos (x-y)=2/3 (4)(2)平方-(1)平方cos2x+cos2y+2(cosxcosy-sinxsiny)=-2/32cos(x+y)cos(x-y)+2cos(x+y)=-2/3把(4)代入,得到cos(x+y)=-1/5所以cosxcosy-sinxsiny=-1/5 (5)由(3)和(5)解得cosxcosy=7/30,sinxsiny=13/30所以tanxtany=sinxsiny/cosxcosy=13/7======以下答案可供参考======供参考答案1:解: 两条件式平方相加,得 2+2cos(x-y)=13/3 →cos(x-y)=7/6矛盾了题目有问题sinx+siny=根号3要改为根号2 解: 两条件式平方相加,得 2+2cos(x-y)=10/3 →cos(x-y)=2/3 …… (1) 两条件式平方相减,得 cos2x+cos2y+2cos(x+y)=-2/3 →2cos(x+y)cos(x-y)+2cos(x+y)=-2/3 代(1)代入,得 4/3*cos(x+y)+2cos(x+y)=-2/3 →cos(x+y)=-1/5 …… (2) (1)+(2),得2cosxcosy=7/15 …… (3) (1)-(2),得2sinxsiny=13/15 …… (4) (4)÷(3),得tanxtany=13/7.

和我的回答一样，看来我也对了