Answer:
It's not a right angle.
Explanation:
Remark
There's a second restriction on the problem. The Perimeter is 22 cm.
AB = 8
BC = 5
AC = 9.4
When you add these up, you get 8 + 5 + 9.4 which is 22.4
You may think this is close enough. In this case it is not. Either the perimeter has to 22.4 or the hypotenuse has to be reduced. Let us say it is close, but not close enough.
When you use other methods, you find out that the right angle is actually 90.4 degrees