化简cos(80°)/1-cos(10°) =
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/27 18:01:40
![化简cos(80°)/1-cos(10°) =](/uploads/image/z/12512585-65-5.jpg?t=%E5%8C%96%E7%AE%80cos%2880%C2%B0%29%2F1-cos%2810%C2%B0%29+%3D)
化简cos(80°)/1-cos(10°) =
化简cos(80°)/1-cos(10°) =
化简cos(80°)/1-cos(10°) =
cos(80°)/1-cos(10°)=sin(10°)/{1-(1-2(sin5°)^2}=2sin5°cos5°/2(sin5°)^2=cot5°
如有不明白,
cos80=sin10=2sin5cos5
1-cos10=2cos²5
所以原式=2sin5cos5/(2cos²5)=sin5/cos5=tan5
cos(80°)/【1-cos(10°)】 =sin10°/{1-【1-2(sin5°)^2】}=2sin5°cos5°/(2sin5°*sin5°)=cot5°(=tan85°)