Question

1-tan22.5度的平方/tan22.5度=?

Answer 1

(1-tan^2(22.5度)) / (tan(22.5度))

= (1 - sin^2(22.5度)/cos^2(22.5度)) / (sin(22.5度)/cos(22.5度))

= (cos(22.5度) - sin^2(22.5度)/cos(22.5度)) / (sin(22.5度))

= (cos^2(22.5度) - sin^2(22.5度)) / (sin(2...