Question

已知函数f(x)满足f(cosx)=x/2(0≤x≤π),则f(-1/2)=（）

A.cos1/2
B.π/4
C.π/3
D.π/2

Answer 1

f(cosx)=x/2(0≤x≤π),
f(-1/2)=f（cos2/3π）=2π/3/2=π/3
选择C

Answer 2

C

Answer 3

C

cosx=-1/2
x=2π/3
f(-1/2)=f(cos2π/3)=2π/3 /2=π/3