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20 12 how to do the third question of 25 questions of the second model mathematics in Miyun senior high school entrance examination.
25. It is known that the side length of diamond ABCD is 1. The two sides of equilateral △AEF intersect DC and CB at points E and F respectively.

(1) Special discovery: As shown in figure 1, if point E and point F are the midpoints of DC and CB sides respectively, it is proved that the intersection point O of diagonal AC and BD of rhombic ABCD is the epicenter of equilateral △AEF;

(2) If point E and point F always move on the sides of DC and CB respectively, remember that the outer center of equilateral △AEF is p. 。

① conjecture verification: as shown in Figure 2, guess which straight line the epicenter P of △AEF falls on and prove it;

② Extended application: As shown in Figure 3, when E and F are the midpoint of DC and CB sides respectively, the intersection point P is regarded as a straight line, the DA side is at M point, the BC side is at G point, and the extension line of DC side is at N point. Please write directly? The value.

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