How to solve shaded regions on a trapezoid is simple. First find the area of the whole trapezoid, or W but it already gives us that as 21.66 in squared. Next, find the area of the non shaded region, or NS. 3.8*4.6=17.48 in Lastly, subtract the NS from the W. 21.66 -17.48 = NS= 17.48 in squared. W= 21.66 in squared. S= 4.18 in squared.