tan67°30'-tan22°30'=?
问题描述：
tan67°30'-tan22°30'=?
不用计算机,简便的!
答
tan67°30'-tan22°30'
=tan67°30'-cot67°30'
=(sin^267°30'-cos^267°30')/(sin67°30'cos67°30')
=-cos135°/sin135°
=-1