Lesson 4 - Perimeter of a Rectangle #1

[One speaker] 

[question: The top of a pizza box forms a square where each side is 35 cm. Find the perimeter of the square defined by this pizza box.]

Narrator: [reads the question] So let’s draw what the top of our pizza box might look like. We know we have a square. [draws a square] And each side is 35 centimeters. [writes 35 cm] and what we recall from the video, we know that our perimeter is equal to two times the length plus two times the width. [p=2l+2w] But in this case, when you have a square, the length is equal to the width. So you can write this as four times the length, or four times the width, either one is acceptable.[p=2l+2w=4l] So in this case our perimeter is going to be equal to four times 35. So let’s plug that into our calculator. We have four times 35 equal 140. [p=4(35)=140.] So we know that our perimeter equals 140, and our units are in centimeters. So we’re going to have 140 centimeters.      

[End of video]