The function y=1cosleft(frac2x3right)y = 1\\cos\\left(\\frac{2x}{3}\\right)y=1cosleft(frac2x3right) has a period TTT. What is the period?
frac2pi2\\frac{2\\pi}{2}frac2pi2
frac4pi3\\frac{4\\pi}{3}frac4pi3
2pi2\\pi2pi
frac6pi2\\frac{6\\pi}{2}frac6pi2