As shown in the figure, in the trapezoidal ABCD, ab ‖ CD, e is the midpoint of AD, EF ‖ CB intersects AB at point F, if BC = 4cm, then the length of EF is______ cm．

As shown in the figure, in the trapezoidal ABCD, ab ‖ CD, e is the midpoint of AD, EF ‖ CB intersects AB at point F, if BC = 4cm, then the length of EF is______ cm．

In △ ADG, EF ‖ DG, e is the middle point of AD, EF = 12bc = 12dg = 12 × 4 = 2cm, so the answer is: 2

The quadrilateral ABCD is a parallelogram, DB is perpendicular to ad, ad = 8cm, BD = 12cm, find the length of BC, AC

BC = ad = 8 in parallelogram
Connect BD, AC do = BD / 2 = 6
In the right triangle ADO, the hypotenuse Ao = 10
Then AC = 2ao = 20

As shown in the figure, B and C divide the line ad into three parts: 2:3:4 & nbsp; m is the midpoint of AD, CD = 8, and find the length of MC______ ．

The total length is: 8 △ 4 × (2 + 3 + 4) = 18, MD = 18 △ 2 = 9, MC = md-cd = 9-8 = 1