Question

已知函数f(x)=二分之根号三Sin2x-cosx的平方-1/2,x属于R

Answer 1

【参考答案】

f(C)=(√3 /2)sin2C-cosC^2-(1/2)

=(√3/2)sin2C-[(cos2C+1)/2]-(1/2)

=sin2Ccos(π/6)-sin(π/6)cos2C-1

=sin(2C- π/6)-1

=0

则 sin(2C- π/6)=1, 即C=π/3

由sinB=2sinA得

b/s...