What is the used of include <cmath> and <iomanip>

Answer 1

The cmath header file in C++ is used to allow the user to perform some math related functions like sqrt(), pow(), cos (), abs () and many more.
iomanip is used for formatting stuffs which includes functions like setw(), setprecision(), etc.

Answer 2

cmath include (you guess it) math function
Iomanip include some easy to use function for formatting, like width and stuff