Amaury draws an acute triangle on the coordinate grid. He finds the area of the triangle by drawing a rectangle that circumscribes the triangle and forming right triangles. How can Amaury find the area of the triangle? What is the area of the triangle in square units??

9 answers

To find the area of an acute triangle using a circumscribing rectangle, Amaury can follow these steps:

  1. Identify the Vertices: Write down the coordinates of the triangle's vertices, which we will call \(A(x_1, y_1)\), \(B(x_2, y_2)\), and \(C(x_3, y_3)\).

  2. Find the Circumscribing Rectangle: Determine the minimum and maximum x-values and y-values from the vertices:

    • Minimum x: \(x_{\text{min}} = \min(x_1, x_2, x_3)\)
    • Maximum x: \(x_{\text{max}} = \max(x_1, x_2, x_3)\)
    • Minimum y: \(y_{\text{min}} = \min(y_1, y_2, y_3)\)
    • Maximum y: \(y_{\text{max}} = \max(y_1, y_2, y_3)\)

    The corners of the rectangle are then \((x_{\text{min}}, y_{\text{min}})\), \((x_{\text{max}}, y_{\text{min}})\), \((x_{\text{max}}, y_{\text{max}})\), and \((x_{\text{min}}, y_{\text{max}})\).

  3. Calculate the Area of the Rectangle: The area of the rectangle is calculated as: \[ \text{Area} = (x_{\text{max}} - x_{\text{min}}) \times (y_{\text{max}} - y_{\text{min}}) \]

  4. Calculate the Area of Each Right Triangle: To find the area of the triangle more easily, Amaury can calculate the area of the rectangle and subtract the areas of the four right triangles formed at the corners.

  5. Determine the Areas of the Right Triangles: For each corner of the rectangle, the right triangles can be calculated. For each:

    • Triangle at \((x_{\text{min}}, y_{\text{min}})\) is formed by the points \(A\), \(B\), and the right angle.
    • Triangle at \((x_{\text{max}}, y_{\text{min}})\):
    • Triangle at \((x_{\text{min}}, y_{\text{max}})\):
    • Triangle at \((x_{\text{max}}, y_{\text{max}})\):

    You will need the coordinates of the points to calculate each area specifically.

  6. Final Area Calculation: The area of the triangle will be the area of the rectangle minus the areas of the four corners' triangles.

However, without specific coordinates, we cannot derive a numerical area. If you can provide the coordinates of the triangle’s vertices, I can help calculate the exact area.

A is, (-3,5) B is, (3,7) C is, (2,3)

To find the area of the triangle with vertices \( A(-3, 5) \), \( B(3, 7) \), and \( C(2, 3) \), we can use the formula for the area of a triangle given its vertices \( (x_1, y_1) \), \( (x_2, y_2) \), and \( (x_3, y_3) \):

\[ \text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| \]

Substituting the coordinates of points \( A \), \( B \), and \( C \):

  • \( A(-3, 5) \) gives \( x_1 = -3 \), \( y_1 = 5 \)
  • \( B(3, 7) \) gives \( x_2 = 3 \), \( y_2 = 7 \)
  • \( C(2, 3) \) gives \( x_3 = 2 \), \( y_3 = 3 \)

Now, plug in the values into the area formula:

\[ \text{Area} = \frac{1}{2} \left| -3(7 - 3) + 3(3 - 5) + 2(5 - 7) \right| \]

Calculating each term:

  1. \( -3(7 - 3) = -3 \times 4 = -12 \)
  2. \( 3(3 - 5) = 3 \times -2 = -6 \)
  3. \( 2(5 - 7) = 2 \times -2 = -4 \)

Now substitute these values back into the area formula:

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

Combine the terms:

\[ \text{Area} = \frac{1}{2} \left| -22 \right| = \frac{1}{2} \times 22 = 11 \]

Thus, the area of the triangle ABC is \( \boxed{11} \) square units.

Write how you got the answer more clearly. Don't use / and [ ]

Sure! Here’s a clearer step-by-step explanation of how to find the area of the triangle with vertices A(-3, 5), B(3, 7), and C(2, 3):

Step 1: Identify the Coordinates

We have three points:

  • Point A has coordinates (-3, 5)
  • Point B has coordinates (3, 7)
  • Point C has coordinates (2, 3)

Step 2: Use the Area Formula for a Triangle

The formula for the area of a triangle when given the coordinates of its vertices (x1, y1), (x2, y2), and (x3, y3) is:

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

Step 3: Substitute the Coordinates

Using the coordinates of our points:

  • x1 = -3, y1 = 5 (for point A)
  • x2 = 3, y2 = 7 (for point B)
  • x3 = 2, y3 = 3 (for point C)

Now substitute these values into the formula:

Area = 1/2 * | (-3)(7 - 3) + (3)(3 - 5) + (2)(5 - 7) |

Step 4: Calculate Each Term Inside the Absolute Value

Calculate the first term:

  • (-3)(7 - 3) = -3 * 4 = -12

Calculate the second term:

  • (3)(3 - 5) = 3 * (-2) = -6

Calculate the third term:

  • (2)(5 - 7) = 2 * (-2) = -4

Now, combine these results:

  • The expression inside the absolute value becomes: -12 - 6 - 4 = -22

Step 5: Find the Area

Now we need to take the absolute value of -22:

  • The absolute value of -22 is 22.

Finally, plug this back into the area formula: Area = 1/2 * 22 = 11

Final Answer:

The area of the triangle ABC is 11 square units.

Please simplify the writing

Sure! Here’s a simplified version of how to find the area of the triangle with vertices A(-3, 5), B(3, 7), and C(2, 3):

  1. Identify Points:

    • A(-3, 5)
    • B(3, 7)
    • C(2, 3)
  2. Use the Area Formula:

    • The formula for the area of a triangle given its vertices is: Area = 1/2 * | x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2) |
  3. Substitute Coordinates:

    • For point A: x1 = -3, y1 = 5
    • For point B: x2 = 3, y2 = 7
    • For point C: x3 = 2, y3 = 3
    • Plugging in the values: Area = 1/2 * | (-3)(7 - 3) + (3)(3 - 5) + (2)(5 - 7) |
  4. Calculate Each Part:

    • (-3)(7 - 3) = -12
    • (3)(3 - 5) = -6
    • (2)(5 - 7) = -4
  5. Combine the Results:

    • Add these values: -12 - 6 - 4 = -22
  6. Find the Area:

    • Take the absolute value: | -22 | = 22
    • Then divide by 2: Area = 1/2 * 22 = 11

Final Result: The area of the triangle is 11 square units.

What does the 1/2 mean?

The \( \frac{1}{2} \) in the area formula for a triangle is a constant that accounts for the fact that a triangle is half of a rectangle or parallelogram.

Explanation:

  1. Area of a Rectangle or Parallelogram:

    • The area of a rectangle is given by the formula \( \text{Area} = \text{base} \times \text{height} \).
    • A triangle can be thought of as half of a rectangle or a parallelogram formed by two identical right triangles.
  2. Why Divide by 2:

    • When you calculate the area of a triangle using its vertices, you're essentially calculating the area of the rectangle or parallelogram that could contain it, but since the triangle only occupies half of that space, the formula includes the \( \frac{1}{2} \) factor to correct for this.

In the Formula:

When we write:

\[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \]

or using the vertex coordinates:

\[ \text{Area} = \frac{1}{2} \times | x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) | \]

the \( \frac{1}{2} \) ensures that we are calculating precisely the area of the triangle and not that of the rectangle or parallelogram containing it.

So, in summary, the \( \frac{1}{2} \) accounts for the fact that a triangle is exactly half of a rectangle when both shapes share the same base and height.