
Topics & Tools
Health Topics
Learn about Perimeter of Irregular Figures Video
 Healthline →
 Videos →
 Learn about Perimeter of Irregular Figures Video
TenMarks teaches you how to find the perimeter of irregular figures.
Read the full transcript »
Learn about Perimeter of Irregular Figures Perimeter of irregular figures: Okay, so in this first problem, we need to find the perimeter of this figure and each square equal 1 cm2. So, before we begin, let’s talk about a perimeter. So, a perimeter is the distance around the outside of a closed figure. So, it's the distance around the outside of a closed figure. Now, we can you find the perimeter of any polygon, if we know the length of each side. So, in order to find the perimeter, we need to know the length of each side. Now, perimeter is the distance covered by the square length around the figure. So, put your finger on one of the corners and mark your starting point one. So, I'm going to mark my starting point here as one. Then we’re going to count the number of square length along the border, the outside of the figure. So, if this is one, this is two, three, four and I'm going to continue doing this around my perimeter. Okay, I'm going to go all the way around the perimeter until I get to the end. So, this will be 31 and then 32. So, I counted. I added all the unit, the square length around my perimeter. So, there are 32 square lengths along the border. So we know there are 32 square lengths along the border. Now, we know each square is 1 cm2. So, each square length measures one centimeter. So this means each square length measures one centimeter because we know that 1 x 1 = 12 which would be 1 cm2. So now, so to find the perimeter P, we would use the formula the number of square length along the border times the length of each. So, the formula that we would use for an irregular figure would be the number of square lengths along the border times the length of each. So, P would equal the number square lengths along the border, is 32 times the length of each, we know each square length is one centimeter. So, it would be times one. So, if I multiply 32 x 1, I get 32 centimeters. So the perimeter of this figure is 32 centimeters. Let’s move on to our second problem. All right here, it states that the sketch of an architect’s plan for a flower garden is given below. How much fencing will be required to enclose the garden? So, here we need the amount of fencing required to enclose this garden. Now, the garden is equal to the perimeter of the garden. So, the fencing is equal to the perimeter. So, when we talk about the fencing, we’re talking about the perimeter. It's going around the garden. Now, we can find the perimeter of any polygon if we know the length of each side. So, we know that the perimeter of the figure is going to equal the number of square lengths along the border times the length of each. So, if I were to again put my finger in one square and start counting each square, four, five. So each square length and I kept going around. When I get to the end, I know that there are 28. So, I know that I have 28 square lengths around my border. Now, we also know that each square equals one yard squared. So that means if each square is one yard squared, then each square length would be one yard because 1 x 1 = 12 which one yard squared. So now we can plug this into our formula. So, P = the square length along the border times the length of each. So, that means P = the square length along the border we know is 28 times the length of each where we said each square length is one yard. So therefor, if I multiply 28 x 1 I get 28 yards. All right, so the amount of fencing required to enclose the garden is 28 yards. All right, things to remember and to keep in mind, is that when we’re talking about the perimeter, the perimeter is the distance around the outside of a closed figure. So to do that, you put your finger in one of the corners of the figure and mark your starting point just like we did here. We marked our starting point and then we count the number of square lengths along the border of the outside. So we kept counting along the border of the outside and we go all the way around until we get to the end. Remember that the fo