tan82.5°=tan(60°+22.5°)=(tan60°+tan22.5°)/(1-tan60°tan22.5°)
tan22.5°=√((1-cos45°)/(1+cos45°))=√(3-2√2)
tan82.5°=(√3+√(3-2√2))/(1-√3√(3-2√2))