why
sin(A/20cos(A/2)+cos(A/2)sin(A/2)+sin(B/2)cos(B/2)+cos(B/2)sin(B/2)
can be simplified as
sin(A/2+A/2)+sin(B/2+B/2) ?
中四數學問題trigonometry(續三角學)
2010-09-17 2:27 am
回答 (1)
2010-09-17 10:10 am
✔ 最佳答案
sin(A/2)cos(A/2)+cos(A/2)sin(A/2)+sin(B/2)cos(B/2)+cos(B/2)sin(B/2)sin(A/2)cos(A/2) + sin(A/2)cos(A/2) + sin(B/2)cos(B/2) + sin(B/2)cos(B/2)
2sin(A/2) cos(A/2) + 2sin(B/2) cos(B/2)
sin(A) + sin(B) [Note that sin 2X = 2 sinX cosX ------- double angle formula]
sin(A/2 +A/2) + sin(B/2 +B/2)
[ A =1/2 A + 1/2 A and B =1/2 B + 1/2 B]
收錄日期: 2021-04-29 16:56:12
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100916000051KK00827