Two radii of two concentric circles are $15$ and $7$. $AB$ is a diameter of the larger circle that intersects the smaller circle at $C$ and $D$. Find the two possible values for $AC$. (the questions has no image)
I think one is $8$. I can't figure out the other one.
Depending on the position of C/D like the comments said, it can be $15-7=8$ or $15+7=22$
Here is the picture btw.