Can someone help with 11-19 please extra points

Which multiplicative property is being illustrated below? (type commutative, associative, or identity) 5 × 2 × 4 = 2 × 5 × 4

The diagonals of a quadrilaretral intersect at (-1,4). one of the sides of the quadrilateral is bounded by (2,7) and (-3,5) determine the coordinates of the other side in order for the quadrilaretral to be a square.

The measure of angle 0 is 600 degrees