已知向量a=(根号3,1)b=(cosπ/3,-sinπ/3)记f(x)=2absinx/2
问题描述:
已知向量a=(根号3,1)b=(cosπ/3,-sinπ/3)记f(x)=2absinx/2
(1)若x∈【0,π】求函数f(x)的值域
(2)在△ABC中若fsinA+sinB的最大值
答
a.b=√3cosπ/3-sinπ/3.
=√3*(1/2)-√3/2;
=0.
f(x)=2absin(x/2).
=0.
(1) f(x)的函数值=0;
(2) f(x)sinA+sinB=0+sinB的最大值=sinB=1.