On the left is a semicircle. Draw a picture. The domain of 9-X is (-3,3), which can be obtained by adding and subtracting three. .

B-a=2 (ab is like a problem here)

Bring b=3 a= 1

So take X= 1 into Y=2 and multiply it by the root number 2.

Therefore, the left-right equation must pass the point 1, and the root sign is twice.

The solution is K= radical number 2

Personally, I think it is better and more difficult to regard it as the focus of a straight line and a semicircle.