A (-1,-2)

B (-2, 0)
C (0,2)
D (2,0)
E (1,-2)

Using each coordinates, what is the perimeter of the polygon? Round each calculations to the nearest tenth.

The perimeter is approximately __ units

1 answer

To find the perimeter of the polygon defined by the points A, B, C, D, and E, we first need to calculate the lengths of the sides connecting each pair of consecutive points.

The formula for the distance \( d \) between two points \( (x_1, y_1) \) and \( (x_2, y_2) \) is:

\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \]

Step 1: Calculate each side length

  1. Distance AB: \[ AB = \sqrt{(-2 - (-1))^2 + (0 - (-2))^2} = \sqrt{(-1)^2 + (2)^2} = \sqrt{1 + 4} = \sqrt{5} \approx 2.2 \]

  2. Distance BC: \[ BC = \sqrt{(0 - (-2))^2 + (2 - 0)^2} = \sqrt{(2)^2 + (2)^2} = \sqrt{4 + 4} = \sqrt{8} \approx 2.8 \]

  3. Distance CD: \[ CD = \sqrt{(2 - 0)^2 + (0 - 2)^2} = \sqrt{(2)^2 + (-2)^2} = \sqrt{4 + 4} = \sqrt{8} \approx 2.8 \]

  4. Distance DE: \[ DE = \sqrt{(1 - 2)^2 + (-2 - 0)^2} = \sqrt{(-1)^2 + (-2)^2} = \sqrt{1 + 4} = \sqrt{5} \approx 2.2 \]

  5. Distance EA: \[ EA = \sqrt{(-1 - 1)^2 + (-2 - (-2))^2} = \sqrt{(-2)^2 + (0)^2} = \sqrt{4} = 2.0 \]

Step 2: Sum the lengths to get the perimeter

Now, we sum the calculated lengths:

\[ \text{Perimeter} = AB + BC + CD + DE + EA \]

Calculating it step-by-step:

\[ \text{Perimeter} \approx 2.2 + 2.8 + 2.8 + 2.2 + 2.0 \]

Calculating each step:

  • \(2.2 + 2.8 = 5.0\)
  • \(5.0 + 2.8 = 7.8\)
  • \(7.8 + 2.2 = 10.0\)
  • \(10.0 + 2.0 = 12.0\)

Final Answer

Thus, the perimeter of the polygon is approximately 12.0 units.