Write the equation for the graph above show all calculations

Write the equation for the graph above show all calculations for y = d + a Cos (bx - c)

amplitude a =(4-(-2))_/2

a=3

mid line y = (4-2)_/2 =1

vertical shift d = 1

period 2/b=4/3

b=3/2

phase shift c/b =

c/(3/2)=

c=3/2

y =1+ 3cos((3_/2)x -(3_/2)) is equation