can 12,16,20 make a right triangle

Answer 1

If it is a right-angled triangle, the largest side would have to be the hypotenuse, so

check if 12^2 + 16^2 = 20^2

or, reduce the numbers by a common factor of 4
that is:
does 12,16,20 form a right-angled triangle ----> does 3,4,5 form a right-angled triangle
(which you should be able to check mentally)

Answer 2

the answer is yes btw