题目

It is true that careful planning and foresight fullness is required for doing investments. But it is also true that knowledge of investment just needs a little study and financial research. Some people are scared of doing investment due to lack of knowledge. Some people think they don't require it. But, nowadays many people are utilizing investment solutions UK for having a prosperous future. Investing in UK land is an opportunity for investors to get astronomical returns with very little downside risks. It does not usually require big chunks of money like conventional property market, where （本小题满分12分）如图所示，正方形与直角      梯形所在平面互相垂直，，，. (Ⅰ)求证：平面； （Ⅱ）求四面体的体积.