 understand law of reflection and law of refraction using Haydn's principle. So we are using Haydn's principle to prove law of refraction because we have when we study the ray optics. Now we are proving it using Haydn's principle. So first of all we keep it Haydn's principle reflection right down again. So suppose this is coming like this or studied reflection in the precedence. Show where it is at the distance. Then I say now same like v4 is basically the uvf of ray and v is the direction of rotation so that should be 90 degrees. 90 degrees. Now this is t. This is the new way of reflection using Haydn's principle. Now we will check similarity in fraction of 1 to 3. So we will write distance of 1 to 3. So 1 to 3 distance. So we get n1 sine i and 2 sine r. This is what the Snell's law is. So you can see that how powerful this principle is Haydn's principle.