Trigonometrical graphs reveal many exciting properties of their functions.
One such function is the "Sinc" function.
This "Sinc" function is represented by the equation (sin x) / x.
NOTE: There is no typo error for the word "Sinc".
This special maths function is the trigonometric sine of an angle divided by that particular angle.
Looking at the graphs of various multiple of sinc functions, you will notice some unique properties in the cross-over angles (markings).
Looking closely at the multiples of radian pi, 2pi and 3pi, you will see that the amplitudes of the various sinc functions are zero.
This is a special characteristics of "Sinc" function.
If you sample these functions at interval of pi, you will get nothing or zero amplitude.
Interesting trigonometry, right?