Exercise 10 - 02/07/2017
1. Write a C++ function to calculate the area of a rectangle. The function will accept 2 double parameters and return a double.

2. Write a C++ function that accepts an integer x and returns its factorial x!. Then, in the main function, use this function to calculate the binomial coefficient of a pair of numbers n and k, which is defined as n!/(k! * (n-k)!)