构造是一种创造能力,就平面几何而言主要是作辅助线,本文以2014年几道中考题为例,谈谈如何构造课本基本图形(如图1常称A字型)解(证)题.例1(湖北黄石)AD是△ABC的中线,将BC边所在直线绕点D顺时针旋转α角,交边AB于点M,交射线AC于点N,设AM=xAB,AN=yAC(x,y≠0).(1)如图2,当△ABC为等边三角形且α=30°时,证明:△AMN∽△DMA; Construction is a kind of creative ability, mainly in terms of plane geometry as a supporting line. In this paper, a few 2014 senior high school entrance examination questions as an example, to talk about how to construct textbook basic graphics (Figure 1 often called A font) Example 1 (Yellowstone, Hubei) AD is the midline of △ ABC, and the line around BC is rotated by angle α clockwise, AB is at point M and AC is at point N, AM = xAB, AN = yAC (x, y ≠ 0). (1) As shown in Figure 2, when △ ABC is equilateral triangle and α = 30 °, it is proved that: △ AMN∽ △ DMA;