Answer:
14.8
Explanation:
Pythagorean theorem! Or however you spell it lol.
So we can see that our triangle here has a little box on it's side. That means it's 90 degrees, so we can work from there and use the pythagorean theorem!
9^2+7^2=c^2 this is what you need to do to find the other side of the rectangle.
81+49=c^2
130=c^2
We can estimate that to be around 11.4!
Now that we know both sides of the rectangle, we can do the pythagorean theorem again (because the dotted line is the hypotenuse)! 9^2+11.4^2=c^2
My gosh this is a lot of work-
81+130=c^2
221=c^2
c=14.8
And so that would be the approximate answer! 14.8. I may be wrong though, so don't take this as 100% right.