See 45, think of isosceles RT△；; ; When you see 60, you think of an equilateral triangle; See the midpoint and think of the midline; Seeing the RT triangle, I thought of Pythagorean theorem. In short, you should think of a graphic when you see its characteristics. For example, an isosceles right triangle has an angle of 45, and when you see an angle of 45, you should think of an isosceles right triangle. For another example, when I see an ugly person, I think his father is even uglier. On the contrary, when I see his ugly father, I think his son is as ugly as he is!

Hope to adopt