A(1, 1), B(7, 1), C(1, 9)
AB = 7 - 1 = 6
AC = 9 - 1 = 8
Use the Pythagorean theorem:
AB² + AC² = BC²
Substitute:
BC² = 6² + 8²
BC² = 36 + 64
BC² = 100 → BC = √100 → BC = 10
The perimeter of ΔABC:
P = 6 + 8 + 10 = 24
