Wednesday, Oct. 11 - AREA & PERIMETER

Here we will learn about how to find area and perimeter of a plane figures. The perimeter is used to measure the boundaries and the area is used to measure the regions enclosed. Watch both videos included in this lesson. They will be important to develop your understanding of area and perimeter. If you have questions, email, text or call me and we can discuss any problems you are having.


The length of the boundary of a closed figure is called the perimeter of the plane figure. The units of perimeter are same as that of length, i.e., m, cm, mm, etc. Basically, think of a fence. It surrounds the perimeter of your yard.


A part of the plane enclosed by a simple closed figure is called a plane region and the measurement of plane region enclosed is called its area. Area is measured in square units. Basically, think of a yard, you measure the length and the width to see how many square feet it is.

Perimeter and Area of Rectangle:

● The perimeter of rectangle = 2(l + w).

● Area of rectangle = l × b; (l and w are the length and width of rectangle)

Perimeter and Area of the Square:

● Perimeter of square = 4 × S (side of the square).

● Area of square = S × S.

Perimeter and Area of the Triangle:

● Perimeter of triangle = (a + b + c); (a, b, c are 3 sides of a triangle)

● Area of triangle = 1/2 × b × h; (b base , h height)


Perimeter and Area of the Circle:

● Perimeter of circle (circumference) = 2nr (n=pi/3.14, r=radius)

● Area of a circle = πr2 (pi/3.14 times the radius squared)

Lesson Video