Have you tried to convert input funtion into float number?
like
variable = float(input('words'))
Because round() function will produce a float output as well.
Besides, the ways to make round() function works:
round(number or number variable, numberdigits)
Following the 3rd question, it would be:
print round(hypotenuse,2)
or
print('A right triangle has hypotenuse', round(hypotenuse,2))