The correct given equation is:
y = 5 + 3 cos 2 (x – π/3)
To answer this problem, we must remember that:
y = A cos [w(x - π)], the period is 2 π / w and the phase shift is π (the beginning of one period)
Rewriting the given equation to this form,
y = 5 + 3cos [2(x - π/3)]
Therefore,
period = 2 π / 2 = π
phase shift = π /3
So to create two periods, you need an interval of 2 π
If you start at π /3, you'll start and end at the max of the cos function.
Therefore,
[Xmin , Xmax] = [π /3 , 7 π /3] would create a complete graph of 2 periods.
ANSWER: [π /3 , 7 π /3]