(Ⅰ)化简 (Ⅱ)已知α,β均为锐角,且sinα= 2 c o s 2 1 2 t a n ( π
−α)si4 π
+α) .4
,sinβ= 2 5 5
,求α﹣β的值.
答案(点此获取答案解析)