Factor this by grouping. Group the first two terms together and then the second 2 terms together. The idea here is that, after grouping, what you can pull out in both groups is the same. Like this:

Now work on finding a common thing between the 2 groups:

See, what you have in common there now is the (x-9) that you can factor out:

And that is factored completely.
Theres no linked picture.
In a right-triangle, if either of the other two angles are "half that measure", or half of 90°, that means 45°, then the last angle will also have to be a 45° one too, and the sides coming from the 90° angle, will be equal twins, and therefore they can only make up one type-length hypotenuse, and due to that, you can only make that one triangle. Check picture below.