唔該幫我計: （要步驟）
1. cos60°cos30°+sin60°sin30° /tan30°
2. 2cos^2 45°-tan45° /sin50°
3.sin31°tan59°-cos31°
4. (1+tan^2 55°)sin^2 35°+1
答案是：
1. 3/2
2.0
3.0
4.2
急急急....sin cos tan
2009-05-04 4:00 am
回答 (1)
2009-05-04 4:31 am
✔ 最佳答案
1. cos60ocos30o+sin60osin30o /tan30o=cos(60o-30o)/tan30o
=cos30o/tan30o
=(√3 /2)/(1/√3)
=3/2
2. 2cos2 45o-tan45o /sin50o
=2(1/2)-1/sin50o
=0/sin50
=0
3.sin31otan59o-cos31o
=sin31o(1/tan31o)-cos31o
=cos31o-cos31o
=0
4. (1+tan2 55o)sin2 35o+1
=(1/cos255o)(sin235o)+1
=(1/cos255o)(cos255o)+1
=2
收錄日期: 2021-04-23 20:39:41
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090503000051KK01852