已知函数f(x)=sin(2x+π/3),设g(x)=f(x)-根号3f(x+π/4),且tana=根号2,求g(a)的值
问题描述:
已知函数f(x)=sin(2x+π/3),设g(x)=f(x)-根号3f(x+π/4),且tana=根号2,求g(a)的值
答
g(x)=sin(2x+π/3)-√3 cos(2x+π/3)=2[0.5sin(2x+π/3)-(√3/2)cos(2x+π/3)]=2sin[2x+(π/3)-(π/3)]=2sin2x已知tana=√2,所以g(a)=2sin2a=4sina*cosa=4*(√2/√3)*(1/√3)=4√2/3谢谢啦我已经知道为什么了~