Math Problem Statement

In a right-angled triangle ABC with ∠B = 90°, the length of side AB = 8 units and the length of side BC = 6 units. Point D is on side AC such that AD: DC=2:3. Point E is on side BC such that BE: EC = 3: 4. If the area of triangle BDE is maximized, what is the ratio of the areas of triangles BDE and ABC?

Your first skill is: Applying Geometric Concepts second skill Applying Propositional Logic

use these skills/topics to solve

Solution

We are tasked with finding the ratio of the areas of triangles BDE\triangle BDE and ABC\triangle ABC, where certain conditions on the positions of points DD and EE apply. Let’s go through this step by step, applying geometric concepts and logical reasoning.

1. Step 1: Analyze Triangle ABC

  • ABC\triangle ABC is a right-angled triangle with B=90\angle B = 90^\circ.
  • The lengths of sides are:
    • AB=8AB = 8 units
    • BC=6BC = 6 units
    • We can calculate the hypotenuse ACAC using the Pythagorean theorem:

AC=AB2+BC2=82+62=64+36=100=10 units.AC = \sqrt{AB^2 + BC^2} = \sqrt{8^2 + 6^2} = \sqrt{64 + 36} = \sqrt{100} = 10 \text{ units}.

2. Step 2: Set up the partition on sides AC and BC

  • Point DD divides side ACAC in the ratio AD:DC=2:3AD:DC = 2:3, meaning AD=25ACAD = \frac{2}{5}AC and DC=35ACDC = \frac{3}{5}AC.

    • AD=25×10=4AD = \frac{2}{5} \times 10 = 4 units.
    • DC=35×10=6DC = \frac{3}{5} \times 10 = 6 units.
  • Point EE divides side BCBC in the ratio BE:EC=3:4BE:EC = 3:4, meaning BE=37BCBE = \frac{3}{7}BC and EC=47BCEC = \frac{4}{7}BC.

    • BE=37×6=1872.57BE = \frac{3}{7} \times 6 = \frac{18}{7} \approx 2.57 units.
    • EC=47×6=2473.43EC = \frac{4}{7} \times 6 = \frac{24}{7} \approx 3.43 units.

3. Step 3: Area of triangle ABC

The area of ABC\triangle ABC is given by:

Area of ABC=12×AB×BC=12×8×6=24 square units.\text{Area of } \triangle ABC = \frac{1}{2} \times AB \times BC = \frac{1}{2} \times 8 \times 6 = 24 \text{ square units}.

4. Step 4: Maximize the area of triangle BDE

To maximize the area of triangle BDE\triangle BDE, we use the geometric fact that the area of any triangle is half the product of its base and height. Here, BEBE is part of side BCBC, and point DD divides side ACAC. The area will depend on how these points divide the triangle, but it's maximized when both DD and EE lie in such a way that the triangle is stretched optimally within ABC\triangle ABC.

5. Step 5: Calculate the ratio of areas

The area of BDE\triangle BDE is a fraction of the area of ABC\triangle ABC, and this fraction depends on the positions of DD and EE. Since DD divides ACAC in the ratio 2:3 and EE divides BCBC in the ratio 3:4, the area of BDE\triangle BDE can be approximated by multiplying these ratios:

Ratio of areas=(25)×(37)=635.\text{Ratio of areas} = \left( \frac{2}{5} \right) \times \left( \frac{3}{7} \right) = \frac{6}{35}.

Thus, the ratio of the areas of triangles BDE\triangle BDE and ABC\triangle ABC is:

635.\boxed{\frac{6}{35}}.

Final Result:

The ratio of the areas of triangles BDE\triangle BDE and ABC\triangle ABC is 635\frac{6}{35}.


Would you like to explore any steps in more detail or clarify any concepts?

Here are 5 related questions you might want to consider:

  1. How do we find the centroid of a triangle, and how could it help in area maximization?
  2. What is the significance of the ratio AD:DC=2:3AD:DC = 2:3 in determining the area?
  3. How would the problem change if point EE divided side BCBC in a different ratio?
  4. Can the area of triangle BDE be further maximized by changing other parameters?
  5. How can we apply similar triangle properties to calculate areas more directly?

Tip: When dealing with ratios in geometry, consider using area proportions based on side divisions, as they can simplify complex area comparisons.

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangles
Area Ratios

Formulas

Pythagorean Theorem: AC = √(AB^2 + BC^2)
Area of Triangle: Area = (1/2) × base × height
Area Ratio based on Segment Division: Ratio = (AD/AC) × (BE/BC)

Theorems

Pythagorean Theorem
Area Proportions of Triangles

Suitable Grade Level

Grades 9-11