Rounded, in Radians

In radians the partners use π. For cos(x) = 0.6 on [0, 2π), arccos(0.6) = 0.9273, so one answer is 0.93, and the other is 2π − 0.9273 = 5.3559, so 5.36.

Subtract from the exact value, not from the rounded one: 2π − 0.93 is 5.3532, which rounds to 5.35, one hundredth off. The board writes each case exactly, x = arccos(0.6) and x = 2π − arccos(0.6), and rounds each one.