Sohan wants to buy a trapezium shaped field. Its sides along the river is parallel to and twice the sides along the road. If the area of this field is 10500 sq metre and the perpendicular distance between the two parallel sides is 100m, find the length of the side along the river.

Let the length of the sides of the field along the road be x m.
Then, length of its sides along the river = 2x m.
Distance between them = 100 m.
Area of trapezium = 1/2 × Sum of parallel sides × Distance between them.
10500 = (2x + x)/2 × 100
10500 = 3x/2 × 100
10500 = 150x
1050/15 = x
70 = x
Road side x = 70 m
River side = 2 × Road side = 2x = 2 × 70 = 140 m