设向量，则向量与向量的夹角为00a0（00a000a000a000a000a0）.https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/4169a74836a04245a3e472e347b686fb.png
举一反三
- 空气与介质<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/1e6362735d6d4ae5a77aaafe5b5b49c7.png" />的分界面为z=0的平面，已知空气中的电场强度为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f8c5f3e89f4d4570a92c23bb118869fb.png" />,则介质中的电场强度<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f7bb30061e904b39a8d53ad541435c18.png" />：() A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c1f29b60a07d4d75aa0f7e1c63a75a2f.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/74f128e456384ac79b8204c33052cbcc.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c87cbdc5e75c40b4b875455ed5bccd28.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/b1117f3f152d413b89e5c221153014a8.png" />
- 已知拉普拉斯变换，则原函数为（00a000a000a000a000a0）https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/8741d17ecd3c4018b38c105582fe5adf.png
- 为求方程<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/ce3ea4db5573483a89d1d732d75e1036.png" >在<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/31ea0f26a7064e83856e0c3a268aa9c5.png" >附近的根，则使得迭代格式<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/2cb16d8f43544cca8adc73fc7dce0dff.png" >一定局部收敛的迭代函数为() A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c52ae5e1d8ca4c51ac71ad740e0bb231.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/54a5d832d2544db7905c50c2c7287f09.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/cdecd203bf8049c5b3faccb7e68a42aa.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/4a5e9a33f10e4d489df882c59db1d545.png" >
- 已知信号<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/82c317e53c6941b59567bc236a6ec9ba.png" >，则奈奎斯特取样频率fs为()。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/7f3cd88d635b4fe0871233447ea5494b.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/53752d34e4c64504bc111e280262e228.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/50d5151b1d3f406185372b2ac9f19f93.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/ad47ea06d5aa4270a8e0089425f0bf6d.png" >
- 已知Z变换Z<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/94487389db974f98b2d38b947ec20d83.png" >，收敛域<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/56b4868c286b4b48a8cec67f9f766670.png" >，则逆变换x（n）为()。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/547656863c8b459da97c366d9321ef13.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/d3572493bf964e2d92fde49d59b632af.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c4aacba69e0445b0ad4db797b3c86d53.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/b9af7d9dccb3446595a3a587492eb92a.png" >