最后在纸上作答发照片,
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/13 06:24:21
最后在纸上作答发照片,
![](http://img.wesiedu.com/upload/1/ae/1ae892bdf27902ad3e7ab5d0d6149e38.jpg)
![](http://img.wesiedu.com/upload/1/ae/1ae892bdf27902ad3e7ab5d0d6149e38.jpg)
![最后在纸上作答发照片,](/uploads/image/z/20126116-28-6.jpg?t=%E6%9C%80%E5%90%8E%E5%9C%A8%E7%BA%B8%E4%B8%8A%E4%BD%9C%E7%AD%94%E5%8F%91%E7%85%A7%E7%89%87%2C)
cos²(a+π/4)
=[ cos(2a+π/2)+1 ]/2
=-(1/2)sin(2a)+1/2
=-(1/2)*(2/3)+1/2
=1/6
已知sin2a=2/3,则cos²(a+4/π)=1/6
=[ cos(2a+π/2)+1 ]/2
=-(1/2)sin(2a)+1/2
=-(1/2)*(2/3)+1/2
=1/6
已知sin2a=2/3,则cos²(a+4/π)=1/6