sinx+siny=2sin[(x+y)/2]cos[(x-y)/2]=1/4 ①
cosx+cosy=2cos[(x+y)/2]cos[(x-y)/2]=1/3 ②
①÷②,得 tan[(x+y)/2]=3/4
tan(x+y)=2tan(x+y)/2/1-tan²(x+y)/2=(3/4)/[1-(3/4)²]=24/7
已知sin x +sin y =1/4,cos x +cos y =1/3,则tan (x +y )的值为.
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