非退化二次曲线

Two theorems on chord at contact equation of a nonsingular conic have been proved.

证明了非退化二次曲线切点弦方程的两个定理。

The article uses the theory of projective geometry to determine the polar and pole of self-conjugate of nonsingular conic without thinking about measure.

用射影几何的理论，抛开度量性质，给出了非退化二次曲线自共轭的极线与极点的射影定位，为现代设计提供了理论依据。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。