Two sisters, Daniel and Sophia, were always rivels when it came to math competitions. One day, Daniel drews a quadrilateral \( ABCD \) on the floor of his room, with \( AB=8 \). After sneaking into Daniel's room, his sister, Sophia, drew the diagonals of this quadrilateral and labeled their point of intersection as \( S \). Wanting to challenge Daniel, she measured \( SA, SB, SC, \) and \( SD \), and wrote these lengths on the quadrilateral: \( SA=4, SB=5, SC=10, SD=4 \). After doing so, Sophia challenged Daniel to find the length of \( CD^2 \). Find the correct answer Daniel should have given.