The formula for area of a trapezoid is: 1/2 (b1+b2) h b1=10 b2=10·2=20 because it stated the side parallel is twice as long as the side above h=10/2=5 because the height is half as long as the give side length area of the trapezoid is: 1/2 (10+20) 5 (5·10)·5 50·5 area of the trapezoid is 250 in²