trigo Q
回答 (3)
2012-05-13 12:10 am
✔ 最佳答案
tan 67.5° - tan 22.5°=tan(67.5° - 22.5°) (1+tan 67.5° x tan 22.5°)
=tan45° (1+ cot 22.5° x tan 22.5°)
=(1) (1+1)
=2
2012-05-13 1:53 am
學識左咪得囉^^
我果本breakthrough diploma ex教 tan 135°/2 - tan 45°/2
之後變[sin(135°/2) cos(45°/2) - sin(45°/2) cos(135°/2)]/ cos(135°/2) cos(45°/2)
=sin(135°/2 - 45°/2)/ [1/2(cos90°+cos45°)]........
你果個方法好過佢果個^^
不過yc果個方法應該係最快
yc & HYPERCUBE, thank you so much!
我果本breakthrough diploma ex教 tan 135°/2 - tan 45°/2
之後變[sin(135°/2) cos(45°/2) - sin(45°/2) cos(135°/2)]/ cos(135°/2) cos(45°/2)
=sin(135°/2 - 45°/2)/ [1/2(cos90°+cos45°)]........
你果個方法好過佢果個^^
不過yc果個方法應該係最快
yc & HYPERCUBE, thank you so much!
2012-05-13 1:41 am
yc's ans is much better than mine!
收錄日期: 2021-04-13 18:41:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120512000051KK00370