求值sin15cos5-sin20/cos15cos5-cos20
答案:2 悬赏:70 手机版
解决时间 2021-01-28 19:26
- 提问者网友：最美的风景
- 2021-01-28 08:55
求值sin15cos5-sin20/cos15cos5-cos20
最佳答案
- 五星知识达人网友：玩世
- 2021-01-28 10:06
题目中，数字后面有“°”吗?
(sin15°cos5°-sin20°)/(cos15°cos5°-cos20°)
=[sin15°cos5°-sin(15°+5°)]/[cos15°cos5°-cos(15°+5°)]
=[sin15°cos5°-(sin15°cos5°+cos15°sin5°)]/[cos15°cos5°-(cos15°cos5°-sin15°sin5°)]
=(-cos15°sin5°)/(sin15°sin5°)
=(-cos15°)/(sin15°)
=-cot15°
=-tan75°
=-tan(45°+30°)
=-(1+√3/3)/(1-√3/3)
=-2-√3。
(sin15°cos5°-sin20°)/(cos15°cos5°-cos20°)
=[sin15°cos5°-sin(15°+5°)]/[cos15°cos5°-cos(15°+5°)]
=[sin15°cos5°-(sin15°cos5°+cos15°sin5°)]/[cos15°cos5°-(cos15°cos5°-sin15°sin5°)]
=(-cos15°sin5°)/(sin15°sin5°)
=(-cos15°)/(sin15°)
=-cot15°
=-tan75°
=-tan(45°+30°)
=-(1+√3/3)/(1-√3/3)
=-2-√3。
全部回答
- 1楼网友：鱼忧
- 2021-01-28 10:34
sin20=sin(15+5)=sin15cos5+cos15sin5
cos20=cos(15+5)=cos15cos5-sin15sin5
sin15cos5-sin20/cos15cos5-cos20
=(sin15cos5-sin15cos5-cos15sin5)/(cos15cos5-cos15cos5+sin15sin5
=-cos15sin5/(sin15sin5
=-cot15
=-2-√3
我要举报
如以上回答内容为低俗、色情、不良、暴力、侵权、涉及违法等信息，可以点下面链接进行举报！
点此我要举报以上问答信息
大家都在看
推荐资讯