Math Problem Statement

(5,0),(−2,6) and (−2,0) Step 2 of 2 : What is the area of the triangle? (Hint: Make use of the midpoint formula if the triangle is isosceles.)

Solution

To find the area of the triangle with vertices at (5,0)(5, 0), (2,6)(-2, 6), and (2,0)(-2, 0), we can follow these steps:

Step 1: Check if the Triangle is Isosceles

A triangle is isosceles if two of its sides are of equal length. We calculate the lengths of the sides using the distance formula:

Distance between (x1,y1) and (x2,y2)=(x2x1)2+(y2y1)2\text{Distance between } (x_1, y_1) \text{ and } (x_2, y_2) = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

  1. Length of side between (5,0)(5, 0) and (2,6)(-2, 6): d1=((2)5)2+(60)2=(7)2+62=49+36=85d_1 = \sqrt{((-2) - 5)^2 + (6 - 0)^2} = \sqrt{(-7)^2 + 6^2} = \sqrt{49 + 36} = \sqrt{85}

  2. Length of side between (5,0)(5, 0) and (2,0)(-2, 0): d2=((2)5)2+(00)2=(7)2=7d_2 = \sqrt{((-2) - 5)^2 + (0 - 0)^2} = \sqrt{(-7)^2} = 7

  3. Length of side between (2,6)(-2, 6) and (2,0)(-2, 0): d3=((2)(2))2+(60)2=0+62=6d_3 = \sqrt{((-2) - (-2))^2 + (6 - 0)^2} = \sqrt{0 + 6^2} = 6

The sides d2d_2 and d3d_3 are not equal to d1d_1, and they aren't equal to each other either. So, the triangle is not isosceles, and we don't need the midpoint formula.

Step 2: Use the Area Formula for a Triangle

For a general triangle with vertices (x1,y1)(x_1, y_1), (x2,y2)(x_2, y_2), and (x3,y3)(x_3, y_3), the area AA can be calculated using the following formula:

A=12x1(y2y3)+x2(y3y1)+x3(y1y2)A = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right|

Substitute the coordinates of the points into the formula:

A=125(60)+(2)(00)+(2)(06)A = \frac{1}{2} \left| 5(6 - 0) + (-2)(0 - 0) + (-2)(0 - 6) \right|

A=125(6)+0+(2)(6)A = \frac{1}{2} \left| 5(6) + 0 + (-2)(-6) \right|

A=1230+12=12×42=21A = \frac{1}{2} \left| 30 + 12 \right| = \frac{1}{2} \times 42 = 21

Final Answer:

The area of the triangle is 21 square units.


Would you like more details on any part of the solution, or do you have any further questions?

Related Questions:

  1. How can we determine if a triangle is isosceles using only the coordinates?
  2. What is the formula to calculate the perimeter of a triangle given its vertices?
  3. How do you find the centroid of a triangle using its vertices?
  4. What is the significance of the determinant in calculating the area of a triangle?
  5. How would the area formula change if the triangle were in 3D space?

Tip:

When dealing with coordinate geometry problems, drawing a rough sketch of the points on the coordinate plane can often help you visualize the problem better and avoid mistakes.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Distance Formula
Area of Triangle

Formulas

Distance formula
Area of triangle formula

Theorems

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Suitable Grade Level

Grades 9-12