#1**+2 **

In my opinion, there's no point of that extra triangle, maybe just there as a red herring...

Anyways, we can use the Pythagorean theorem on 12 and 6 to get y.

We know that:

a^{2 }+ b^{2 }= c^{2}

Here is a lovely little picture that could help you wrap your mind around how it works:

So, what does this tell us? Well, now we know this now:

12^{2 }= 6^{2 }+ y^{2}

This now means:

144 = 36 + y^{2}

^{Simplify:}

108 = y^{2}

Which means:

y = sqrt(108) = **6sqrt(3)**

**:)**

ilorty Sep 1, 2020