To find the area of an irregular shape, you also need to know each of the angles. You can then divide the figure into several regular shapes, like triangles and rectangles, calculate the area of each piece, and add them together. I would add... convert yards to feet and divide by 43,560. (sq feet in one acre)
To calculate the area of the plot in square yards, you multiply the dimensions together: 430.24 yards * 260.55 yards * 466.75 yards * 80.17 yards = 42,255,981.24 square yards. To convert square yards to acres, divide by 4840 (since 1 acre is equal to 4840 square yards). Therefore, the plot of land is approximately 8739.06 acres.