((cos20°)^2-1)*(1-3^(1/2)tan10°)这么算
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/25 18:23:38
![((cos20°)^2-1)*(1-3^(1/2)tan10°)这么算](/uploads/image/z/3712610-2-0.jpg?t=%28%28cos20%C2%B0%29%5E2-1%29%2A%281-3%5E%281%2F2%29tan10%C2%B0%29%E8%BF%99%E4%B9%88%E7%AE%97)
((cos20°)^2-1)*(1-3^(1/2)tan10°)这么算
((cos20°)^2-1)*(1-3^(1/2)tan10°)这么算
((cos20°)^2-1)*(1-3^(1/2)tan10°)这么算
会不会是(cos²10°-1)*(1-√3tan10°)
cos²10°-1)*(1-√3tan10°)
=[(1+cos20°)/2-1]*(1-√3tan10°)
=[(cos20°-1)/2]*[(cos10°-√3sin10°)/cos10°]
=[(cos20°-1)/2]*[2sin20°/cos10°]
=2(cos20°-1)sin10°
=2cos20°sin10°-2sin10°
=1/2-3sin10°