How to Find the Area and Perimeter of a Square, Triangle, Rectangle, and Circle

Calculate Area

• 1

  Calculate the area of a square or rectangle. Measure the length and width of the shape. Multiply the figures to get the area.

• 2

  Calculate the area of a circle. Measure the diameter and divide that figure by 2 to get the radius. Multiply the radius by itself, so that it is squared. Multiply the squared radius by 3.14. The result is the area of the circle.

• 3

  Calculate the area of a triangle. Measure the base and height (from the point to the base). Divide the base measurement by 2. Multiply half the base by the height to get the area.

Calculate Perimeter

• 4

  Calculate the perimeter of a square or rectangle by measuring the length of each side, then adding each figure together.

• 5

  Calculate the perimeter of a triangle by adding the lengths of the three sides.

• 6

  Measure the radius of a circle. Multiply the radius by 2 and by pi, which is approximately 3.14. The result is the perimeter of a circle, also known as circumference.