Find the 6 Trig ratios of -7Pie/3
-7π/3 is coterminal with - π/3 or +5π/3
(-420° is coterminal with -60° or +300°)
using the reference of π/3, and the CAST rule
sin ( -7π/3) = -√3/2
cos ( -7π/3) = +1/2
tan ( -7π/3) = -√3
I will let you state the other three.