1. If AB is tangent to the circle, then
[tex]18^2=(2\cdot7.2)^2+10.8^2[/tex]
We have
[tex]18^2=324[/tex]
[tex](2\cdot7.2)^2+10.8^2=324[/tex]
so AB is indeed tangent to the circle.
2. The unlabeled leg is another radius of the circle so it has length 8. Then if AB is tangent to the circle,
[tex](10+8)^2=8^2+15^2[/tex]
but we have
[tex](10+8)^2=324[/tex]
[tex]8^2+15^2=289[/tex]
so that cannot be a right triangle and AB is not tangent to the circle.
