I have tried doing this but can't seem to get a handle on it.

In row 1 I want to enter a variable in A1, solve the cosine of that variable in A2,enter a constant in A3 and solve the sum of the cosine of the variable times the constant in A4. I want to repeat this with a variable value in column A. Example:

A-cos 30(Z)=

B-cos 45(Z)=

C-cos 60(Z)=...etc.