[Fred Hayek]

Sorry about the delay, I had to reboot my internet connection. Sine of 45 degrees (or pi/8 radians if you prefer) is one of those things a person memorized, along with the sine of 30 degrees and 60 degrees.

[dr_lew]

Sine of 45 degrees (or pi/8 radians if you prefer) is one of those things a person memorized.

Does one memorize it ? Like "Arms and the man" ? Or does one KNOW it, by its definition?