What does the changing wave value in brackets mean?

GHS report：

Wave type: TROCHOID
Phase of crest relative to origin: 0.0 degrees (0.00 Ft)
Wave length: 80.00 Ft Crest-to-trough height: 4.00 Ft
。。
Phase of crest relative to origin: 10.0 degrees (2.22 Ft)

Phase of crest relative to origin: 20.0 degrees (4.44 Ft)

Phase of crest relative to origin: 30.0 degrees (6.67 Ft)

Phase of crest relative to origin: 40.0 degrees (8.89 Ft)
Phase of crest relative to origin: 50.0 degrees (11.11 Ft)