Math Problem Statement

CONNECTING CONCEPTS The lines $y_1=2x-6$ , $y_2=-3x+4$ , and $y_3=-\frac{1}{2}x+4$ intersect to form the sides of a right triangle. Find the perimeter, to the nearest hundredth and area of the triangle. Perimeter: units

Area: square units

Solution

To find the perimeter and area of the triangle formed by the lines y1=2x6y_1 = 2x - 6, y2=3x+4y_2 = -3x + 4, and y3=12x+4y_3 = -\frac{1}{2}x + 4, we'll need to do the following steps:

  1. Find the points of intersection of the three lines.
  2. Calculate the lengths of the sides of the triangle.
  3. Determine if it's a right triangle by checking if the Pythagorean theorem holds.
  4. Compute the perimeter and area of the triangle.

Step 1: Find the points of intersection

Let's find the points of intersection of each pair of lines.

  • Intersection of y1=2x6y_1 = 2x - 6 and y2=3x+4y_2 = -3x + 4: 2x6=3x+42x - 6 = -3x + 4 5x=10x=25x = 10 \quad \Rightarrow \quad x = 2 Substitute x=2x = 2 into either equation to find yy: y=2(2)6=46=2y = 2(2) - 6 = 4 - 6 = -2 So, the intersection point is (2,2)(2, -2).

  • Intersection of y1=2x6y_1 = 2x - 6 and y3=12x+4y_3 = -\frac{1}{2}x + 4: 2x6=12x+42x - 6 = -\frac{1}{2}x + 4 5x2=10x=4\frac{5x}{2} = 10 \quad \Rightarrow \quad x = 4 Substitute x=4x = 4 into either equation to find yy: y=2(4)6=86=2y = 2(4) - 6 = 8 - 6 = 2 So, the intersection point is (4,2)(4, 2).

  • Intersection of y2=3x+4y_2 = -3x + 4 and y3=12x+4y_3 = -\frac{1}{2}x + 4: 3x+4=12x+4-3x + 4 = -\frac{1}{2}x + 4 5x2=0x=0-\frac{5x}{2} = 0 \quad \Rightarrow \quad x = 0 Substitute x=0x = 0 into either equation to find yy: y=12(0)+4=4y = -\frac{1}{2}(0) + 4 = 4 So, the intersection point is (0,4)(0, 4).

Thus, the vertices of the triangle are (2,2)(2, -2), (4,2)(4, 2), and (0,4)(0, 4).

Step 2: Calculate the lengths of the sides

We calculate the distances between each pair of points:

  • Length of side ABAB between (2,2)(2, -2) and (4,2)(4, 2): AB=(42)2+(2(2))2=4+16=204.47AB = \sqrt{(4 - 2)^2 + (2 - (-2))^2} = \sqrt{4 + 16} = \sqrt{20} \approx 4.47

  • Length of side BCBC between (4,2)(4, 2) and (0,4)(0, 4): BC=(40)2+(24)2=16+4=204.47BC = \sqrt{(4 - 0)^2 + (2 - 4)^2} = \sqrt{16 + 4} = \sqrt{20} \approx 4.47

  • Length of side CACA between (0,4)(0, 4) and (2,2)(2, -2): CA=(20)2+(24)2=4+36=406.32CA = \sqrt{(2 - 0)^2 + (-2 - 4)^2} = \sqrt{4 + 36} = \sqrt{40} \approx 6.32

Step 3: Determine if it's a right triangle

To verify if the triangle is a right triangle, check if the Pythagorean theorem holds: AB2+BC2=?CA2AB^2 + BC^2 \stackrel{?}{=} CA^2 (4.47)2+(4.47)220+20=40(4.47)^2 + (4.47)^2 \approx 20 + 20 = 40 CA2=6.32240CA^2 = 6.32^2 \approx 40 Since the sums match, the triangle is indeed a right triangle.

Step 4: Compute the perimeter and area

  • Perimeter: Perimeter=AB+BC+CA4.47+4.47+6.32=15.26 units\text{Perimeter} = AB + BC + CA \approx 4.47 + 4.47 + 6.32 = 15.26 \text{ units}

  • Area: Since it's a right triangle, the area can be calculated using the formula: Area=12×base×height\text{Area} = \frac{1}{2} \times \text{base} \times \text{height} Here, the base and height are ABAB and BCBC (or vice versa): Area=12×4.47×4.4710.00 square units\text{Area} = \frac{1}{2} \times 4.47 \times 4.47 \approx 10.00 \text{ square units}

Final Answers:

  • Perimeter: 15.26\approx 15.26 units
  • Area: 10.00\approx 10.00 square units

Would you like more details or have any questions?

Here are some related questions:

  1. What is the significance of verifying the triangle as a right triangle?
  2. How would the solution change if the triangle were not right?
  3. Can you determine the centroid of this triangle?
  4. What would happen if one of the lines were parallel to the x-axis?
  5. How can you find the circumcenter of this triangle?

Tip: In coordinate geometry, always verify the type of triangle using distance formulas and check for special properties like being right-angled.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Intersection of Lines
Distance Formula
Pythagorean Theorem
Area of Triangle

Formulas

Distance formula
Pythagorean theorem
Area of a triangle

Theorems

Pythagorean theorem

Suitable Grade Level

Grades 9-12