1试题呈现(南京卷第27题)折纸的思考。操作体验用一张矩形纸片折等边三角形。第一步,对折矩形纸片ABCD(AB>BC)(图1(1)),使AB与DC重合,得到折痕EF,把纸片展平(图1(2))。第二步,如图1(3),再一次折叠纸片,使点C落在EF上的P处,并使折痕经过点B,得到折痕BG,折出PB、PC,得到△PBC。 1 questions presented (Nanjing volume 27 questions) origami thinking. Operating experience with a rectangular sheet folded equilateral triangle. The first step is to fold the rectangular paper ABCD (AB> BC) (Figure 1 (1)) so that AB and DC coincide, resulting in folds EF flattening the paper (Figure 1 (2)). The second step, as shown in Figure 1 (3), once again folded the paper, so that the point C fell on the EF on the P, and the crease through the point B, get crease BG, off PB, PC, △ PBC .