Draw a rectangle on the grid with an area of 1575 sq units and a side of 45 units

The area of a rectangle is calculated by multiplying the measure of the sides. That is the length and the width. 
             Area = length x width

To determine the measure or length of one pair of parallel sides of the rectangle, the area is divided by the given dimension of the sides.
                   Length = Area / width
                  Length = (1575 sq units) / (45 units)
                  Length = 35 units

Hence, to draw the rectangle, two pair parallel sides will have the lengths of 45 and 35 units.