根据f(0)=-0 ,可得 tanb=-3 .
sin(2x+b)+3cos(2x+b)
=sin2xcosb+cos2xsinb+3cos2xcosb-3sin2xsinb
=sin2x(cosb-3sinb)+cos2x(sinb+3cosb)
=sin2xcosb(1-3tanb)+cos2xcosb(tanb+3)
=10sin2xcosb
不知道对不对啊,你好好看一下
根据f(0)=-0 ,可得 tanb=-3 .
sin(2x+b)+3cos(2x+b)
=sin2xcosb+cos2xsinb+3cos2xcosb-3sin2xsinb
=sin2x(cosb-3sinb)+cos2x(sinb+3cosb)
=sin2xcosb(1-3tanb)+cos2xcosb(tanb+3)
=10sin2xcosb
不知道对不对啊,你好好看一下