Math Problem Statement

How can you determine the area of the triangle with the following coordinates: (-2,6), (5,4), (2,-2).

Solution

To determine the area of a triangle given three coordinates, you can use the shoelace formula (or determinant formula). The formula is:

Area=12x1y2+x2y3+x3y1(y1x2+y2x3+y3x1)\text{Area} = \frac{1}{2} \left| x_1 y_2 + x_2 y_3 + x_3 y_1 - (y_1 x_2 + y_2 x_3 + y_3 x_1) \right|

Given the coordinates of the triangle:

  • A(2,6)A(-2, 6)(x1,y1)(x_1, y_1)
  • B(5,4)B(5, 4)(x2,y2)(x_2, y_2)
  • C(2,2)C(2, -2)(x3,y3)(x_3, y_3)

We can substitute the values into the formula.

Step 1: Identify the coordinates

  • x1=2,y1=6x_1 = -2, y_1 = 6
  • x2=5,y2=4x_2 = 5, y_2 = 4
  • x3=2,y3=2x_3 = 2, y_3 = -2

Step 2: Apply the shoelace formula

Area=12(2)(4)+(5)(2)+(2)(6)[(6)(5)+(4)(2)+(2)(2)]\text{Area} = \frac{1}{2} \left| (-2)(4) + (5)(-2) + (2)(6) - \left[ (6)(5) + (4)(2) + (-2)(-2) \right] \right|

Step 3: Simplify

First, calculate each part: Area=12(8)+(10)+12[30+8+4]\text{Area} = \frac{1}{2} \left| (-8) + (-10) + 12 - \left[ 30 + 8 + 4 \right] \right| Area=12642\text{Area} = \frac{1}{2} \left| -6 - 42 \right| Area=12×48\text{Area} = \frac{1}{2} \times 48 Area=24\text{Area} = 24

So, the area of the triangle is 24 square units.


Would you like more details on this method, or have any questions about the steps?

Related questions:

  1. How would you calculate the area of a triangle given vertices with decimals?
  2. What is the meaning of the "shoelace formula" and why it works for area calculation?
  3. How do you calculate the area of a triangle using Heron's formula?
  4. How can the coordinates of a triangle's centroid be determined?
  5. How would you calculate the area of a triangle in 3D space?

Tip: The shoelace formula is especially useful when you have the exact coordinates of the vertices, and it’s applicable to any polygon when you can define the points in order.

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Math Problem Analysis

Mathematical Concepts

Geometry
Coordinate Geometry
Area Calculation

Formulas

Shoelace Formula (Determinant Formula)

Theorems

Shoelace Theorem

Suitable Grade Level

Grades 9-11