Consider x cm as the smaller side of the trapeziumSo the larger parallel can be written as (x + 4) cmWe know that the area of trapezium = 21​× sum of parallel sides × heightBy substituting the values475=21​×(x+(x+4))×19On further calculation25=21​×(2x+4)So we get50 = 2x + 4By subtraction2x = 50 - 42x = 46By divisionx = 23cmSo we get Larger parallel side (x + 4) = 23 + 4 = 27cmTherefore, the length of two parallel sides is 23cm and 27cm.