Coverage for triangles.py: 68%

1"""Functions for working with triangles. 

2 

3A triangle is represented by a tuple (a, b, c), 

4which defines the length of the three sides. 

5""" 

6 

7import math 

8 

9 

10def valid(tri): 

11 """Check if a tuple represents a valid triangle. 

12 

13 Args: 

14 tri (tuple): length of the three sides 

15 

16 Returns: 

17 bool: True if valid, False otherwise 

18 """ 

19 # if not exactly three sides 

20 if len(tri) != 3: 

21 return False 

22 a, b, c, = sorted(tri) 

23 # if any side is not positive 

24 if a <= 0: 

25 return False 

26 # longest side is not too long 

27 return c < a + b 

28 

29 

30def area(tri): 

31 """Calculate the area using Heron's Formula. 

32 

33 Args: 

34 tri (tuple): length of the three sides 

35 

36 Returns: 

37 float: area of the triangle 

38 """ 

39 if not valid(tri): 

40 raise ValueError("invalid triangle") 

41 # calculate half the perimeter 

42 a, b, c, = tri 

43 s = 0.5 * (a + b + c) 

44 # calculate the triangle area 

45 return math.sqrt(s * (s-a) * (s-b) * (s-c)) 

46 

47 

48def classify(tri): 

49 """Determine the type of triangle. 

50 

51 Args: 

52 tri (tuple): length of the three sides 

53 

54 Returns: 

55 str: "Equilateral", "Isosceles", or "Scalene" 

56 """ 

57 if not valid(tri): 

58 raise ValueError("invalid triangle") 

59 a, b, c = tri 

60 if a == b == c: 

61 return "Equilateral" 

62 elif a == b or b == c or a == c: 

63 return "Isosceles" 

64 else: 

65 return "Scalene" 

66 

67 

68if __name__ == "__main__": 

69 t = (3, 4, 5) 

70 print(f"valid({t}):", valid(t)) 

71 print(f"area({t}):", area(t)) 

72 print(f"classify({t}):", classify(t))