Answer :
No. The two legs (6 and 6) have to add up to longer than the hypotenuse (12)
Very technically, yes. But . . .
-- Its angles would be 0°, 0°, and 180° .
-- Its height and area would both be zero.
-- It would look like a line segment, because the two ' 6 ' legs
would have to be wide open in a straight line, and they would
lie right on top of the ' 12 ' leg ... that's the only way they could
reach between the ends of it.