The simplest way to draw ellipses with perpendicular sides is to model them by using a closed string, like a ruler. You can also use a strip of paper with length a+b, where a is the center and b is the outside diameter of the ellipse. Once you’veunderstood the conceptof tangents,...
说起北外五年级七班的26个孩子,不能不竖起大拇指.他们因为参与数学活动,所以喜欢上了数学.数学小讲师平时孩子们的数学课不是老师讲,而是孩子们在老师的引导下讲给小伙伴听.孩子们讲的不局限于书本上的数学知识,还延伸到课外,他们经常会在班级群里分享一些趣题.数学小灵通(5-6年级)...