Use a Calculator to Give the Real Number Value $$y = \cos ^ { - 1 } ( 0.8910 )$$

Use a calculator to give the real number value. Round the answer to 7 decimal places.
- $$y = \cos ^ { - 1 } ( 0.8910 )$$

A) $1.1000010$
B) $0.5063492$
C) $0.4365083$
D) $0.4712533$