在三角形ABC中,AB=7,BC=5,CA=6,则向量AB×向量BC=我知道答案等于-19可我算的等于19但是COSB算出来不是19/35吗,那么向量AB×向量BC=5乘以7乘以19/35=19?为什么是负的?
来源:学生作业帮助网 编辑:作业帮 时间:2024/09/04 11:56:42
![在三角形ABC中,AB=7,BC=5,CA=6,则向量AB×向量BC=我知道答案等于-19可我算的等于19但是COSB算出来不是19/35吗,那么向量AB×向量BC=5乘以7乘以19/35=19?为什么是负的?](/uploads/image/z/1812398-14-8.jpg?t=%E5%9C%A8%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E4%B8%AD%2CAB%3D7%2CBC%3D5%2CCA%3D6%2C%E5%88%99%E5%90%91%E9%87%8FAB%C3%97%E5%90%91%E9%87%8FBC%3D%E6%88%91%E7%9F%A5%E9%81%93%E7%AD%94%E6%A1%88%E7%AD%89%E4%BA%8E-19%E5%8F%AF%E6%88%91%E7%AE%97%E7%9A%84%E7%AD%89%E4%BA%8E19%E4%BD%86%E6%98%AFCOSB%E7%AE%97%E5%87%BA%E6%9D%A5%E4%B8%8D%E6%98%AF19%2F35%E5%90%97%2C%E9%82%A3%E4%B9%88%E5%90%91%E9%87%8FAB%C3%97%E5%90%91%E9%87%8FBC%3D5%E4%B9%98%E4%BB%A57%E4%B9%98%E4%BB%A519%2F35%3D19%3F%E4%B8%BA%E4%BB%80%E4%B9%88%E6%98%AF%E8%B4%9F%E7%9A%84%3F)
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