The circle with a radius of one unit is partitioned into twelve equal arcs, where each arc corresponds to specific t-values. Determine the value of the trigonometric function at the given real number t using the (x,y) coordinates in the diagram or specify that the expression is undefined. Also, find out the value in part b) using even and odd properties of trigonometric functions.
a. cos(4π/3)
b. cos(-4π/3)

• A. cos(4π/3) = -(√2)/2, cos(-4π/3) = -(√2)/2
• B. cos(4π/3) = -1/2, cos(-4π/3) = -1/2
• C. cos(4π/3) = (√2)/2, cos(-4π/3) = (√2)/2
• D. cos(4π/3) = (√2)/2, cos(-4π/3) = -(√2)/2

Answer: (B)