三角學的應用
回答 (2)
2014-05-18 11:25 pm
✔ 最佳答案
cos77°- (cos13°/tan77°) =cos77°- [cos13°/(sin77°/cos77°)]
=cos77°- [(cos13°cos77°)/sin77°]
=cos77°- [(cos13°cos77°)/cos(90°-77°)]
=cos77°- [(cos13°cos77°)/cos13°]
=cos77°- cos77°
=0
2014-05-18 15:27:44 補充：
解釋:
tan77°=sin77°/cos77°
sin77°=cos(90°-77°)=cos13°
SO
tan77°=cos13°/cos77°
2014-05-18 11:13 pm
按小算盤就計到，有什麼難度﹖以前沒有小算盤就要查對數表。
收錄日期: 2021-04-13 22:24:11
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20140518000051KK00086