Math Problem Statement

Review the following image containing a prompt, the model response, and the final answer. Prompt: Two triangles share a common vertex at the coordinate A(0, 0). One triangle is located above the x-axis, while the other is below. . The vertices of the upper triangle are A(0, 0), B(-2, 3), and C(2,3). . The vertices of the lower triangle are A(0,0), B'(-1 ,- 3), and C'(1 ,- 3). Find the area of the triangle formed by the vertices A', B', and C', where A' is the intersection point of segments BC' and B'C. Solution: The equation of the line BC' passing through B(-2, 3) and C'(1, - 3) is determined as follows: -3-3 -6 m = 1 - (-2) . =- 2 y-3 =- 2(x+2) = y =- 2x-1 The equation of the line B'C passing through B'(-1 ,- 3) and C(2,3) is: 3 -(-3) _0 =2 m = 2- (-1) 3 y-(-3)= 2(x+1) = y=2x-1 To find A', the intersection of BC' and B'C, solve the system: y =- 2x-1 and y=2x-1 Equating: -2x-1=2x-1 =- 2x=2x=x=0 Substitute x = 0 into y = - 2x -1: y =- 1 Thus, A'(0 ,- 1). The vertices of the triangle A'B'C' are A'(0 ,- 1), B'(-1 ,- 3), and C'(1 ,- 3). To calculate the area, use the formula: Area = > |x1(V2 - y3) + x2(V3 - y1) + x3(V1 - y2)| 1 Substituting (x1,y1)=(0 ,- 1),(x2,y2)=(-1 ,- 3).(x3,y3)=(1 ,- 3): Area = - 10(-3- (-3)) + (-1)(-3-(-1))+1((-1)-(-3))| Area = - 10+(-1)(-2) + 1(3)| Area = >10+2+3|=>×5=2.5 Final Answer: The area of the triangle A'B'C' is: 2.5 square units

Solution

The solution you provided outlines the method to find the area of the triangle formed by the vertices A'(-1, -3), B'(-1, -3), and C'(1, -3) after determining the intersection point A' using the equations of the lines BC' and B'C. Let’s go over the steps and correct a few parts of the solution where necessary:

Step 1: Equation of Line BC'

  • The line passes through points B(-2, 3) and C'(1, -3).
  • The slope mm is calculated as: m=y2y1x2x1=331(2)=63=2m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{-3 - 3}{1 - (-2)} = \frac{-6}{3} = -2
  • The point-slope form of the line is: y3=2(x+2)y - 3 = -2(x + 2) Simplifying the equation: y=2x1y = -2x - 1 Correct.

Step 2: Equation of Line B'C

  • The line passes through points B'(-1, -3) and C(2, 3).
  • The slope mm is calculated as: m=3(3)2(1)=63=2m = \frac{3 - (-3)}{2 - (-1)} = \frac{6}{3} = 2
  • The point-slope form of the line is: y+3=2(x+1)y + 3 = 2(x + 1) Simplifying the equation: y=2x1y = 2x - 1 Correct.

Step 3: Find Intersection (Point A')

  • Set the two equations equal to each other: 2x1=2x1-2x - 1 = 2x - 1 Solve for xx: 2x=2xx=0-2x = 2x \quad \Rightarrow \quad x = 0
  • Substitute x=0x = 0 into one of the equations (e.g., y=2x1y = -2x - 1): y=2(0)1=1y = -2(0) - 1 = -1 So the intersection point is A'(0, -1). Correct.

Step 4: Calculate the Area of Triangle A'B'C'

  • The vertices of the triangle are A'(0, -1), B'(-1, -3), and C'(1, -3).
  • Using the area formula for a triangle with vertices (x1,y1)(x_1, y_1), (x2,y2)(x_2, y_2), and (x3,y3)(x_3, y_3): Area=12x1(y2y3)+x2(y3y1)+x3(y1y2)\text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| Substituting in the coordinates: Area=120((3)(3))+(1)((3)(1))+1((1)(3))\text{Area} = \frac{1}{2} \left| 0((-3) - (-3)) + (-1)((-3) - (-1)) + 1((-1) - (-3)) \right| Simplifying each term: Area=120+(1)(2)+1(2)\text{Area} = \frac{1}{2} \left| 0 + (-1)(-2) + 1(2) \right| Area=120+2+2=12×4=2\text{Area} = \frac{1}{2} \left| 0 + 2 + 2 \right| = \frac{1}{2} \times 4 = 2

Final Answer:

The area of the triangle A'B'C' is 2 square units, not 2.5 as stated in the final answer.


Corrections:

  • The final area calculation is 2 square units, not 2.5 square units.

Would you like to go over any more details about this solution? Let me know if you have any further questions or need additional clarification!

Here are a few related questions to deepen your understanding:

  1. How would you find the area of a triangle if you only had the lengths of the sides?
  2. How can you verify the correctness of a line equation using a graph?
  3. What are the geometric properties of the intersection of two lines in a plane?
  4. How would the area change if one of the points in the triangle was moved?
  5. What other methods exist for finding the area of a triangle in a coordinate plane?

Tip: When finding the area of a triangle using coordinates, always double-check the signs and terms in your area formula to avoid errors in calculation.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Line Equations
Area of a Triangle

Formulas

Area = 1/2 * |x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)|

Theorems

Point of Intersection of Two Lines
Area of Triangle using Coordinates

Suitable Grade Level

Grades 10-12