//Example number 7.4, Page number 7.15

clc;clear;close

// Variable declaration
h=2 // in m
k=2// in m
l=0// in m
a=450 // in m

// Calculations
d=a/(sqrt(h^2+k^2+l^2)) // in m

// Result
printf("d(220) = %.1f pm",d)