Sum the product of two colmuns of data?

I need to sum the results of an operation using two different columns of numbers. Basically:

A1*cos(B1)+A2*cos(B2)+...A500*cos(B500)

with some constants thrown in. Is it possible to put an operation like this in the sum function and get it to work? I know I could make a new column of data with the function and sum that to get what I need, but I have to do this 300 times so I don't want to handle that much data if at all possible.

Thanks in advance!