1.如图1,BD是口通BCD的对角线,点E、F在刀2)上,要使四边形A ECF是平行四边形,还要添加的一个条件是(填上你认为正确的一个即可). 2.如图2,正方形ABCD的边长为8,M在DC上,且刀乃仁2,N是AC上的一个动点,则D八件月夕刀的最小值为 3.四边形ABCD各内角的比为乙A:乙B:乙C:乙D=1:2:3:4, 1. As shown in Figure 1, BD is the diagonal of BCD, and points E and F are on knife 2). To make quadrilateral A ECF a parallelogram, one condition to add is (fill in the one you think is correct. ) 2. As shown in Figure 2, the side length of the square ABCD is 8, M is on the DC, and the knife is a move point on the AC, and the minimum value of the D eight-monthly knife is 3 The ratio of the inner corners of the quadrilateral ABCD is B: A B B: B C: B D = 1:2:3:4,