## Elementary Geometry for College Students (6th Edition)

We assign coordinates for the rectangle: $(0,0); (0,2a); (2b,2a); (2b,0)$ Thus, we find the length of each side: $s_1 = \sqrt{b^2 + a^2}$ $s_2 = \sqrt{b^2 + a^2}$ $s_3 = \sqrt{b^2 + a^2}$ $s_4 = \sqrt{b^2 + a^2}$ The sides are equal lengths, so it is a rhombus.