1.25 mm, 1 mm, 0.75 mm. is this a right triangle?

28 in, 21 in, 20 in
is this a right triangle?

please answer both i have to turn this in, in an hour!

1. Yes it is a right triangle.
1.25^2 = 1^2 + 0.75^2
1.5625 = 1 + 0.5625
1.5625 = 1.5625
Both sides are equivalent therefore it is a right triangle.

2. No it is not a right triangle.
28^2 = 21^2 + 20^2
782 = 441 + 400
782 does not equal 841 therefore it is not a right triangle.

The correct answer is -4