Sine, cosine, tangent and cotangent

2000005406

Level: 
B
Which of the following statements is not true?
Functions f(x)=cos(x+π6) and g(x)=sin(xπ6) are equal.
Functions f(x)=2cos3x is even and its range of values is [1;3].
Functions f(x)=cos(xπ3) and g(x)=sin(x+π6) are equal.
Functions f(x)=cosx and g(x)=sin(x+π2) are equal.