Standing 2.5 m in front of a plane mirror with your camera, you decide to take a picture of yourself without turning the camera around. To what distance should the camera be focused to get a sharp image?
问题描述：
Standing 2.5 m in front of a plane mirror with your camera, you decide to take a picture of yourself without turning the camera around. To what distance should the camera be focused to get a sharp image?
答
在一面平的镜子之前以你的照相机站着 2.5 m ，你决定在没有将照相机转回头下照一张你自己的照片。到什么距离照相机应该被集中焦点在拿一个锐利的图像吗？
答
5m,the distance from the image in the plane mirror to the mirror equal the distance from you to the mirror.