Calculate the internal angles of a regular polygon with N sides This is a simple challenge: given n in any way practical (Function arg, stdin, file, constant in code) output the internal angles 
(NOT the sum of the internal angles, just one) of a regular polygon with n sides. The output can be in degrees, gradians or radians, and can be displayed in any way practical (Function return, stdout, stderr if you feel like it, file etc)

As usual, smallest byte count wins.
Perl 6, 8 bytes



π- τ/*


Try it online!

Output in radians. Simple function in WhateverCode notation which computes \$π-τ/n\$. \$τ\$ is the constant tau equaling \$2π\$.