my question in (ddistance between two point )
show that the quadrilateral with vertices K(3,4),L(2,0),M(-3,-2), and N(-1,3) is a kit ?
What is a kit? Do you mean kite-shaped? That would be a quadrilateral with an axis if symmetry, and two pairs of adjacent equal-length sides. Calculate the distances between the points and see what you get.
For example, the distance from K to L is
sqrt (4^2 + 1^2) = sqrt 17 = 4.123
and the distance from N to K is sqrt(4^2 + 162) = sqrt 17 = 4.123
Prove the other two are equal to each other and you will have proven a "kite".