Basic C program help

[Marcus Ashley]

I have a program that I have to design that computes the distance between two cities in the northern hemisphere. It is supposed to ask for the latitude and longitude of two points then display the distance using spherical and rectangular coordinates. This is also assuming the (rho) of the earth is 3960.
I think i may be making this too hard and I just dont know any ways to use the tangential functions. Any help would be appreciated and im not expecting someone to write this for me. Thanks

[Dy7SLyTq]

div and mod i believe