Math Problem Statement

Find the area and perimeter of the polygon formed by points A(-2, 2), B(0, 4), C(4, 2), D(4, -2), and E(-2, -2).

Solution

To find the area and perimeter of the polygon in the image, we first identify the coordinates of the points labeled AA, BB, CC, DD, and EE based on the grid.

Coordinates of the points:

  • A(2,2)A(-2, 2)
  • B(0,4)B(0, 4)
  • C(4,2)C(4, 2)
  • D(4,2)D(4, -2)
  • E(2,2)E(-2, -2)

Step 1: Calculate the Area

We can use the Shoelace Theorem (or Surveyor's Formula) to calculate the area of a polygon when the coordinates of its vertices are known.

The formula for the area is:

Area=12x1y2+x2y3++xny1(y1x2+y2x3++ynx1)\text{Area} = \frac{1}{2} \left| x_1y_2 + x_2y_3 + \dots + x_ny_1 - (y_1x_2 + y_2x_3 + \dots + y_nx_1) \right|

Using the coordinates A(2,2)A(-2, 2), B(0,4)B(0, 4), C(4,2)C(4, 2), D(4,2)D(4, -2), E(2,2)E(-2, -2), we substitute them into the formula:

Area=12(24)+(02)+(42)+(42)+(22)(20)(44)(24)(22)(22)\text{Area} = \frac{1}{2} \left| (-2 \cdot 4) + (0 \cdot 2) + (4 \cdot -2) + (4 \cdot -2) + (-2 \cdot 2) - (2 \cdot 0) - (4 \cdot 4) - (2 \cdot 4) - (-2 \cdot -2) - (-2 \cdot -2) \right|

Simplifying:

Area=12(8)+(0)+(8)+(8)+(4)(0)(16)(8)(4)(4)\text{Area} = \frac{1}{2} \left| (-8) + (0) + (-8) + (-8) + (-4) - (0) - (16) - (8) - (4) - (4) \right| Area=1228=14 square units\text{Area} = \frac{1}{2} \left| -28 \right| = 14 \text{ square units}

Step 2: Calculate the Perimeter

The perimeter is the sum of the lengths of all the sides. The distance between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is given by the distance formula:

d=(x2x1)2+(y2y1)2d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

Now, let's calculate the distance between each pair of consecutive points:

  1. Distance ABAB: dAB=(0(2))2+(42)2=22+22=4+4=8=22d_{AB} = \sqrt{(0 - (-2))^2 + (4 - 2)^2} = \sqrt{2^2 + 2^2} = \sqrt{4 + 4} = \sqrt{8} = 2\sqrt{2}

  2. Distance BCBC: dBC=(40)2+(24)2=42+(2)2=16+4=20=25d_{BC} = \sqrt{(4 - 0)^2 + (2 - 4)^2} = \sqrt{4^2 + (-2)^2} = \sqrt{16 + 4} = \sqrt{20} = 2\sqrt{5}

  3. Distance CDCD: dCD=(44)2+(22)2=0+(4)2=16=4d_{CD} = \sqrt{(4 - 4)^2 + (-2 - 2)^2} = \sqrt{0 + (-4)^2} = \sqrt{16} = 4

  4. Distance DEDE: dDE=(24)2+(2(2))2=(6)2+0=36=6d_{DE} = \sqrt{(-2 - 4)^2 + (-2 - (-2))^2} = \sqrt{(-6)^2 + 0} = \sqrt{36} = 6

  5. Distance EAEA: dEA=(2(2))2+(2(2))2=0+(4)2=16=4d_{EA} = \sqrt{(-2 - (-2))^2 + (2 - (-2))^2} = \sqrt{0 + (4)^2} = \sqrt{16} = 4

Now, sum all the distances to find the perimeter:

Perimeter=22+25+4+6+4\text{Perimeter} = 2\sqrt{2} + 2\sqrt{5} + 4 + 6 + 4 Perimeter=14+22+25\text{Perimeter} = 14 + 2\sqrt{2} + 2\sqrt{5}

You can either leave the perimeter in this simplified radical form or calculate the approximate decimal value:

Perimeter14+2(1.414)+2(2.236)=14+2.828+4.47221.3 units\text{Perimeter} \approx 14 + 2(1.414) + 2(2.236) = 14 + 2.828 + 4.472 \approx 21.3 \text{ units}

Final Answers:

  • Area: 1414 square units
  • Perimeter: 14+22+2514 + 2\sqrt{2} + 2\sqrt{5} or approximately 21.321.3 units

Would you like more details on any step or have any questions? Here are some follow-up questions:

  1. How does the Shoelace Theorem work in three-dimensional space?
  2. How do you convert a polygon's area formula into integrals?
  3. What are some alternative methods for calculating the perimeter of polygons?
  4. Can the area of irregular polygons always be calculated using the Shoelace Theorem?
  5. How does the distance formula generalize to higher dimensions?

Tip: For polygons on a

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Geometry
Coordinate Geometry
Polygons
Distance Formula
Shoelace Theorem

Formulas

Area using Shoelace Theorem: A = (1/2) |x1y2 + x2y3 + ... + xny1 - (y1x2 + y2x3 + ... + ynx1)|
Perimeter using Distance Formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2)

Theorems

Shoelace Theorem

Suitable Grade Level

Grades 8-10