Question

I can’t seem to get my function to work. When I type in 3 for a, 2 for b, and 3.61 for c. That works. However, when I try those values in a different order (Ex: 3.61 for a, 3 for b and 2 for c) It returns as false. I can’t figure out what the problem is. Thanks in advance!

a = input("Enter a ")
b = input("Enter b ")
c = input("Enter c ")


def isright_angled():
    if abs((a**2+b**2)-(c**2)) < 0.1 or abs((c**2-a**2)-(b**2)) < 0.1 or abs((c**2-b**2)-(a**2)) < 0.1:                         
        return True
    else:
        return False

print isright_angled()

Answer 1

The hypotenuse, if the triangle is right-angled, will be the largest of a, b and c. You can use that to avoid duplicating the test 3 times (this is the “don’t repeat yourself” principle). A second thing to avoid is that if something: return True else: return False. It’s usually better expressed as simply return something. Thirdly, functions can take arguments rather than relying on global variables: this makes things easier to understand and there’s then less chance of functions interfering with each other. I find a * a easier to understand than a ** 2 but that’s personal taste. Putting all that together:

def is_approximately_right_angled(a, b, c):
    a, b, c = sorted([a, b, c])
    return abs(a * a + b * b - c * c) < 0.1

a = input('enter a ')
b = input('enter b ')
c = input('enter c ')
print is_approximately_right_angled(a, b, c)

If it’s not working, you can speed up your development by adding some checks. If you were writing a big program you can write unit tests, but here just some asserts in the module will avoid you having to type a, b, c in each time to test.

I’d add something like this (before the a = input... line):

assert is_approximately_right_angled(3, 4, 5)
assert is_approximately_right_angled(3, 5, 4)
assert is_approximately_right_angled(3, 2, 3.61)
assert not is_approximately_right_angled(3, 5, 5)

With these lines in place, you can have some confidence in the code before you get to type numbers in. When you find cases where the code doesn’t work you can add them as additional checks.