Ok, in order to solve this you need to remember the pythagorean theory which is “a squared + b squared = c squared”
We have to work backwards to be able to find what b squared is. Let’s first square 10 and 19. That gives us 100 and 361.
Now all you have to do is subtract 100 from 361 and square root that number.
This gives us 16.1 inches i believe.
I hope this helped !
<3