Glass mirrors were the latest cutting edge technology in the middle ages, but the convex mirror was the only shape possible.

玻中世纪最新的尖端技术，但凸面唯一可能的形状。

It did have kind of these convex mirrors.

它确实有这种凸面。

These mirrors are convex, causing rays to converge into a real image, which is then magnified through an eyepiece or projected directly onto a digital sensor.

这些凸面的，使光线会聚 成真实图像，然后通过 放大或直接投射数字传感器上。

Remember, the substance of  what she's found so far is that if you look at any convex solid, then the average area for its shadow  is going to be proportional to its surface area.

请记，前为止她发现的实质内容， 如果您观察任何凸面实体，那么其阴影的平均面积将与其表面积成正比。