Pick the best desperation

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.

The serenity and the mystic are sail boats. the serenity and the mystic start at the same point and travel away from each other in opposite directions. the serenity travels at 16 mph and the mystic travels at 19 mph. how far apart will they be in 3 hours?

Given sin28.4=.4756, cos28.4=.8796, and tan28.4=.5407 find the cos of 61.6