​Trig help with homework

5.

a.  Minimum height  =  .5        Max height  =  4

b.  It will reach a minimum after 1 second

c.  Height after  2.5 seconds  =  

Note : cos (2.5 pi)  =  same as cos (pi/2)  =  0

1.75cos (2.5 pi ) + 2.25  =  1.75 (0) + 2.25  =   2.25

Here's a graph : https://www.desmos.com/calculator/lcxviz3ffb