Solution: The area of a circular sector is \( A = \frac\theta360 \pi r^2 \). Original area: \( \frac90360 \pi (12)^2 = 36\pi \). New radius: \( 12 + 4 = 16 \) meters. New area: \( \frac90360 \pi (16)^2 = 64\pi \). The increase is \( 64\pi - 36\pi = 28\pi \). \boxed28\pi - Nelissen Grade advocaten