> tan(π/8) would be halfway between 0 and 1 ie .5?
It implies that tan(π/8) would be "halfway" between 0 and 1 in this sense of what "halfway" means. In this sense, 0.5 is not halfway between 0 and 1, 0.414 is.
It's easier to visualize it. You're standing on the roof of a 1-meter-tall building on a flat earth with a perfectly clear atmosphere. If you look straight out
(90°) you can see to infinity (tan 90°). If you look down (0°) you can see where you are (tan 0°). If you look halfway between those (45°), you can see 1 (tan 45°) meter straight in front of you. But if you look halfway down again, you won't see exactly 0.5 meters, will you?
It implies that tan(π/8) would be "halfway" between 0 and 1 in this sense of what "halfway" means. In this sense, 0.5 is not halfway between 0 and 1, 0.414 is.
It's easier to visualize it. You're standing on the roof of a 1-meter-tall building on a flat earth with a perfectly clear atmosphere. If you look straight out (90°) you can see to infinity (tan 90°). If you look down (0°) you can see where you are (tan 0°). If you look halfway between those (45°), you can see 1 (tan 45°) meter straight in front of you. But if you look halfway down again, you won't see exactly 0.5 meters, will you?