TenMarks teaches you how to find the perimeter of a figure on a coordinate graph.
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How to Find Perimeter on a Coordinate Graph Perimeter on a Coordinate Graph In this problem, the first part we need to find the perimeter of the rectangle. Here we have our rectangle and to find the perimeter of a polygon. A rectangle is a polygon, so to find the perimeter of a polygon; we have to add the length of all sides. So, the rectangle has two equal horizontal and two equal vertical sides. Remember, the perimeter is the sum of lengths of all four sides. In finding the perimeter, the first step that we need to do is find the length of the horizontal. We’re going to look for the horizontal length. If you notice that this does not have it labeled, however, it’s on a coordinate plane, so we have our coordinates. When you have coordinates, coordinates are given in x, y. So, the x coordinate is the first number in each ordered pair. So, for the horizontal length, the x coordinates are 2 and 5. The length of the horizontal line is going to be the difference between the x coordinates, so it’s going to be 5 - 2. So, 5 - 2 is 3 units. The horizontal sides are three units each. This is 3 and this is 3, three units each. Our second step is we need to find the length of the vertical sides, so now we’re looking at the vertical sides. The y coordinate in a set of ordered pair is the second number. To find the length of the vertical line segment which is the width of the rectangle, we need to find the distance between the y coordinates. These are the y coordinates. Notice how it’s the same on both sides. So, the length of the vertical line is going to be the difference between the y coordinates, so it will be 3 - 1.and 3- 1 is 2 units. So, the vertical sides are two units each. So, it’s two units on this side and two units on the other side. Now, our third step in solving this is we need to add the lengths of the sides to find the perimeter. We’re going to find the perimeter by adding the sum of all four lengths. So, the perimeter is the sum of all four lengths. We’re going to go ahead and add them up. I’m going to add the horizontal lengths. I’m going to take 3 + 3 and then I’m going to add the vertical lengths, 2 + 2. When we add these up, we get 10. So, the perimeter of the rectangle is 10 units. Let’s move on to the second problem. Here we need to find the perimeter of this figure. The first step we need to do is we need to label all the coordinates marked in the figure. I’m going to go ahead to label all my parts, so I’m going to say that this A, B, C, D, E and F. I’m labeling my points and now, I’m going to mark all the coordinates. Coordinate A is going to be, remember it’s x, we do coordinates in x,y. So, A is 3 and 2, B is 3 and 8, C is 8 and 8, D is 8 and 5, E is 6 and 5 and then F is 6 and 2. So, they are the six coordinates of this figure. We need to find what the horizontal lines are. Our horizontal lines are going to be B and C is a horizontal line. We also have E and D are horizontal lines and we also have A and F as a horizontal line. Now, we need to find our vertical lines. Our vertical lines go up and down. So, we have A and B, we have C and D and we have E and F. Now, we have gotten all our information that we need in order to find the perimeter of this figure. Our first step that we’re going to do is we need to find the length of the horizontal sides of the figure. So, first thing let’s do is we need to find the length of B, C. So, the length of B, C, we need to look at the x coordinate and remember the x coordinate is the first number in each ordered pair and remember, the ordered pair is B, C. So, the x coordinate for B is 3 and then the x coordinate for C is 8. We’re going to take the difference. So B, C is going to equal 8 - 3 which would give us 5 units. Similarly, let’s find D and E. So, you can put it D, E, or E, D; it’s both the same. So D, E, we look at the x coordinates and we get 8 and 6. So, 8 - 6 would give us 2 units and then we have F and A. F and A is 6 and 3 which would give us three units. Now, we