C2 = $A$1 + B2 = 26 + 53 = 79 ;
C3 = $A$1 + B3 = 26 + 21 = 47.
#!/usr/bin/python3
import math
a = 1.0
b = 2.0
c = 3.0
A = math.degrees(math.acos(math.radians(((b**2 + c**2 - a**2) / 2 * b * c))))
B = math.degrees(math.acos(math.radians(((a**2 + c**2 - b**2) / 2 * a * c))))
C = math.degrees(math.acos(math.radians(((a**2 + b**2 - c**2) / 2 * a * b))))
ravnobedr = (a == b and a == c) or (a == b and b == c) or (a == c and b == c)
ravostor = a == b == c
priamoug = A == 90 or B == 90 or C == 90
ostroug = A < 90 or B < 90 or C < 90
tupoug = A > 90 or B > 90 or C > 90
print(
'''
равнобедренный {}
равносторонний {}
прямоугольный {}
остроугольный {}
тупоугольный {}
'''.format(
ravnobedr,
ravostor,
priamoug,
ostroug,
tupoug,
)
)