The document discusses calculating the area of a circle. It defines radius as the distance from the center of a circle to any point on the circle. It also defines pi as the ratio of a circle's circumference to its diameter, which is approximately 3.14. The formula provided for calculating the area of a circle is Area = pi × radius squared. An example problem calculates the area of a circle with a radius of 3 cm as 28.26 cm squared. The document goes on to use these formulas to find the total area of a basketball key and the half circle above the free throw line, calculating it as 284.52 square feet.