A worker charges $70 per square foot to install windows. How much does it cost to install the window shown? A window. It is composed of a trapezoid on top of a rectangle. The rectangle has a length of 3.5 feet and a width of 1 foot. The trapezoid has base lengths of 3.5 feet and 2.5 feet. The height of the window is 2.5 feet, which is equal to the width of the rectangle plus the height of the trapezoid.