http://www.ck12.org Chapter 10. Perimeter and Area
10.1 Area and Perimeter of Rectangles
Here you’ll learn how to find the area and perimeter of rectangles and squares.
What if Ed’s parents were getting him a new bed, and he had to decide what size bed is best for him? Initially he
decided that he would like a king bed. Upon further research, Ed discovered there are two types of king beds, an
Eastern (or standard) King and a California King. The Eastern King has 76×80 dimensions, while the California
King is 72×84 (both dimensions arewidth×length). Which bed has a larger area to lie on? Which one has a larger
perimeter? If Ed is 6’4”, which bed makes more sense for him to buy? After completing this Concept, you’ll be able
to use your knowledge of rectangles to answer these questions.
Watch This
MEDIA
Click image to the left for more content.CK-12 Foundation: Chapter10AreaandPerimeterofRectanglesA
MEDIA
Click image to the left for more content.MathMade Easy: Finding the Areaof Rectangles
Guidance
To find thearea of a rectanglecalculate the product of its base (width) and height (length)A=bh. Theperimeter
of a rectangleisP= 2 b+ 2 h, wherebis the base (or width) andhis the height (or length). If a rectangle is a
square, with sides of lengths, the formula forperimeterisPsquare= 2 s+ 2 s= 4 sand the formula forareais
Asquare=s·s=s^2.
Example A
Find the area and perimeter of a rectangle with sides 4 cm by 9 cm.
The perimeter is 4+ 9 + 4 + 9 = 26 cm. The area isA= 9 · 4 = 36 cm^2.
Example B
The area of a square is 75in^2. Find the perimeter.