VBA to repeat the process of calculation

hi,
I am new to VBA. I want to calculate distance between 2 latitude longitude data. I know the formula to calculate. But I want VBA to repeat process.

Column A has latitude and Column B has longitude.
The column Header has Latitude and Longitude (A1B1)
The data starts from A2B2 till bottom.
In Cell C2D2 the data from A3B3 should be pasted.
Again, in the same way, data from A4B4 should be pasted to C2D2 only.


I want code to do the above operation.

thanks in advance,