clear
//
//
//

//Variable declaration
d=2.82*10^-10;    //lattice spacing(m)
sintheta=1;   
n=1;

//Calculation
lamda_max=2*d*sintheta/n;    //longest wavelength(m)

//Result
printf("\n longest wavelength is %0.3f angstrom",lamda_max*10^10)