The formula for the volume of a cone is V = (1/3)πr²h. Given radius (r) = 3.5 cm and height (h) = 12 cm, we calculate V = (1/3) (22/7) (3.5)² 12 = (1/3) (22/7) 12.25 12 = (1/3) (22/7) (49/4) 12 = 154 cm³.