Answer:
y = cos(3x +π/6)
y = sin(3x -4π/3)
Explanation:
The period of the function is 2π/3, so the multiplier of x is (2π)/(2π/3) = 3.
Each horizontal division is equivalent to an angle of (1/3)(π/6) = π/18 radians. The cosine function is shifted 1 division to the left. The corresponding sine function is shifted 8 divisions to the right.
Shift of a function by k units to the right is accomplished by replacing x with (x-k).
The function could be written as either of ...
y = cos(3(x +π/18)) = cos(3x +π/6)
y = sin(3(x -8π/18)) = sin(3x -4π/3)