//Example 1_23
clc();
clear;
//To calculate the smallest thickness of the plate
lemda=5890                          //units in angstroam
lemda=5890*10^-10                  //units in mts
u=1.5
r=60                         //units in degrees
t=lemda/(2*u*cos(r*%pi/180))*10^10
printf("The smallest thickness of the plate %.0f angstroam",t)