Henry is asked to find the exact value of cosine StartFraction 10 pi Over 3 EndFraction. His steps are shown below. 1. Subtract 2 pi from StartFraction 10 pi Over 3 EndFraction as many times as possible:
StartFraction 10 pi Over 3 EndFraction – 2 pi = StartFraction 4 pi Over 3 EndFraction
2. Find the reference angle for StartFraction 4 pi Over 3 EndFraction: StartFraction 3 pi Over 2 EndFraction – StartFraction 4 pi Over 3 EndFraction= StartFraction pi Over 6 EndFraction.
3. The cosine value for StartFraction pi Over 6 EndFraction is StartFraction StartRoot 3 EndRoot Over 2 EndFraction.
4. The cosine value is positive because StartFraction pi Over 6 EndFraction is in the first quadrant.

Which of the following describes Henry’s errors?