So, there's a quadrilateral ABCD

How would I find how long AD are?

The point for A is (4,4)
for D s (2,1)

Is there some way to solve this without using a formula?

Well, you could plot the points on a graph and measure the distance bewteen them. Or, you could use the formula

(distance)^2 = (x2 - x1)^2 + (y2 - y1)^2
= 2^2 + 3^2 = 13
The distance between A and D is sqrt13 = 3.6056