Move the slider slowly. What shape do you see in the middle?
a = 24,
b = 18,
c = 30.0
a² + b² =
576 + 324
= 900 = c² ✓
Conservation of area
Outer square (a+b)² = 1,764
4 triangles 4×½ab = 864
White area = c² = 900 ✓