thou should use tau instead of pi pi is wrong
there is a theorum going around that one should use tau instead of pi
tau is a cute little symbol that looks like the greek numeral t
tau= 6.28318530717958647692528676655900576839433879875021
16419498891846156328125724179972560696506842341359
64296173026564613294187689219101164463450718816256
google search it
and you will never use pi again