+0  
 
+1
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Thank you so much

 Apr 2, 2018
 #1
avatar+3994 
+1

Is it 3? Bottom base: 4+9=13, right-angled triangle, so z=12, x=5. If we know one side is 5, and the other side is 4, y=3..

 Apr 2, 2018
 #2
avatar+98061 
+1

Let's look at this one closely......

 

Here's a pic :

 

 

We have  altitude  BC  drawn to a right angle in  triangle ABD

Note that triangle ABC  is similar to triangle CBD

 

Thus

 

AB / BC  = CB / BD     which implies that

 

4 / BC  = BC / 9        cross-multiply

 

36  = BC^2       take the square root of both sides

 

6  = BC  = "y"

 

Thus,  altitide BC in  this situation serves as a geometric mean to the two bases of each of the smaller triangles formed

 

 

 

 

cool cool cool

 Apr 2, 2018

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