Need with numbers 3-4 i don't understand

There is diarrhea on the floor. what do i do? my mum gonna see that i diarrhea on the floor! * don't report, i'm serious! *

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.

Need showing work for this problem 56.25 ×25.80