Finding the Length of a Diagonal in a Rectangle

In the figure below, rectangle ABCD is drawn with vertices A(1, 3), B(1, 6), C(4, 6), and D(4, 3). To find the length of diagonal AC, use the distance formula, which is given by:

$$d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$$

Calculate the distance between points A and C.