Methods Analysis task! help please.

[NeedHelpWithStudy]

Well how do i do the general formulae for the ratio? I'm so lost please help me!
s1(t)= = 3e^(-0.4t) , s2(t) = -3e^(-0.4t) , s3(t) = 3cos(pit) , s(t)= 3e^(-0.4t) *cos(pit)
Questions :
- sketch the graphs of all 4 graphs over an appropriate domain on seperate axes, Discuss the key features of the graphs and any relationship  between the graphs.
- Determine the turning points of your graphs of s(t) and the point of contact between s(t) and s1(t) and s(t) and s2(t).
- What is the relationship (if any) between s(t) and s3(t).
- Develop a general formulae for the magnitude of the successive local minima and for the points of contact.
- Investigate how magnitude of successive local maxima change over time as the swing moves.
- Find the ratios of the successive local maxima.
- Develop the general formula for the ratio of the successive maxima.
s(t) is displacement.
t is time.
displcement in metres
and t in seconds
basically the equations were in this form :
s1(t)= = 3e^(-kt) , s2(t) = -3e^(-kt) , s3(t) = 3cos(ct) , s(t)= 3e^(-kt) *cos(ct)
so we had to choose 1 value for k and c and i chose k = 0.4 and c = pi