已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?sin{π/2-(a+π/4)}=?sin(π/4-a)=?
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/06 19:47:36
![已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?sin{π/2-(a+π/4)}=?sin(π/4-a)=?](/uploads/image/z/5170546-10-6.jpg?t=%E5%B7%B2%E7%9F%A5a%E4%B8%BA%E9%92%9D%E8%A7%92%2Csin%28a%2B%CF%80%2F4%29%3D1%2F3%2C%E5%88%99cos%28a%2B%CF%80%2F4%29%3D%3F%E5%B7%B2%E7%9F%A5a%E4%B8%BA%E9%92%9D%E8%A7%92%2Csin%28a%2B%CF%80%2F4%29%3D1%2F3%2C%E5%88%99cos%28a%2B%CF%80%2F4%29%3D%3Fsin%7B%CF%80%2F2-%28a%2B%CF%80%2F4%29%7D%3D%3Fsin%28%CF%80%2F4-a%29%3D%3F)
已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?sin{π/2-(a+π/4)}=?sin(π/4-a)=?
已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?
已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?sin{π/2-(a+π/4)}=?sin(π/4-a)=?
已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?已知a为钝角,sin(a+π/4)=1/3,则cos(a+π/4)=?sin{π/2-(a+π/4)}=?sin(π/4-a)=?
因为a为钝角
而sin(a+π/4)>0
所以a+π/4还是钝角
所以cos(a+π/4)