你好,
5+6|x|>17
|x|>2
x>2或x设cosx=-3/5,且sina.cosa<0,求2sin(a+π)-3tana/4cos(a-2π)设cosa=-3/5,且sina.cosa<0

则sina=4/5, tana=4/3
2sin(a+π)-3tana/4cos(a-2π)=-2sina-3tana/4cosa=1/15