Thread: Help me, this problem make me 'confuse'

I'm a new joiner, I hope I enjoy with this forum.

I have a problem, look this picture:


Maybe somebody can solve this with simply way? help me...
Thnx..

Note : AD = 8
BC = 10
EF = 4
CD = .......

Don`t has more information?

for example that triangle ACD is rectangle

ACD not a rectangle, but rigt triangle, same like BCD
There is no other information. just like that.
EF is perpendicular form cross of AD and BC.

hm... it's difficult for me..
I get this question from old book - that I have loose it
but I remember this question.
the information just like that.

ACD not a rectangle, but rigt triangle, same like BCD
There is no other information. just like that.
EF is perpendicular form cross of AD and BC.

hm... it's difficult for me..
I get this question from old book - that I have loose it
but I remember this question.
the information just like that.