Let the sides of trapezium be 5x and respectively. According to the question, \( \Large \frac{1}{2}\times(5x+3x)\times 12 \)=384 => 8x=\( \Large \frac{384\times 2}{12} \) => x=\( \Large \frac{64}{8} \)=8 cm Length of smaller of the parallel sides = \( \Large 8\times 3 \) = 24 cm