#1**+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..

tertre
Apr 2, 2018

#2**+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

CPhill
Apr 2, 2018