Question 1011586
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length of EC?
AD= 11, BD = 3, BC = 12, AE = 9 
http://imgur.com/Jh2lmZT
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Hello,

1) In your plot the point A is invisible, but I suspect it is upper vertex.
2) You didn't mention that the straight line DE is parallel to BC. 
   It is important part of the condition.

OK. Now, the triangles ABC and ADE are similar. It gives a proportion

{{{abs(AB)/abs(AD)}}} = {{{abs(AC)/abs(AE)}}},   or   {{{(11+3)/11}}} = {{{(9+x)/9}}},   or   {{{14/11}}} = {{{(9+x)/9}}}

where x is an unknown length of EC.

Simplify and solve it for x.

14*9 = 11*(9+x)  ---->  126 = 99 + 11x  ----->  11x = 126-99 = 27  -----> x = {{{27/11}}}.

The data BC = 12 is excessive for this problem.
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