Math Problem Statement

Right triangle ABC has side lengths AB = 5, AC = 12, and BC = 13. A point X is randomly chosen from the interior of triangle ABC. Find the probability that triangle ABX has area greater than 25. Give your answer as a reduced fraction.

Solution

We are tasked with finding the probability that triangle ABX\triangle ABX, where point XX is randomly chosen inside triangle ABC\triangle ABC, has an area greater than 25.

Step-by-step Solution:

  1. Find the area of triangle ABC\triangle ABC: Since triangle ABC\triangle ABC is a right triangle, we can use the formula for the area of a triangle: Area of ABC=12×base×height\text{Area of } \triangle ABC = \frac{1}{2} \times \text{base} \times \text{height} Here, the base AB=5AB = 5 and the height AC=12AC = 12. So, the area is: Area of ABC=12×5×12=30\text{Area of } \triangle ABC = \frac{1}{2} \times 5 \times 12 = 30

  2. Understanding the problem geometrically: The point XX is randomly chosen from within the triangle ABC\triangle ABC. When we select point XX, the triangle ABX\triangle ABX will have an area that is some fraction of the area of ABC\triangle ABC.

    Since ABC\triangle ABC has an area of 30, we want to find the probability that the area of triangle ABX\triangle ABX is greater than 25.

  3. Set up the proportion: The area of triangle ABX\triangle ABX can be written as a fraction of the area of triangle ABC\triangle ABC. Let λ\lambda be the fraction such that the area of ABX\triangle ABX is λ×30\lambda \times 30. We need to solve for when this area is greater than 25: λ×30>25\lambda \times 30 > 25 Solving for λ\lambda: λ>2530=56\lambda > \frac{25}{30} = \frac{5}{6}

  4. Determine the probability: Since XX is randomly chosen from within ABC\triangle ABC, the area ratio follows a uniform distribution. The probability that the area of ABX\triangle ABX is greater than 25 corresponds to the fraction of λ\lambda values greater than 56\frac{5}{6}.

    The possible values of λ\lambda range from 0 to 1. Thus, the probability that λ>56\lambda > \frac{5}{6} is: P(λ>56)=156=16P(\lambda > \frac{5}{6}) = 1 - \frac{5}{6} = \frac{1}{6}

Final Answer:

The probability that the area of triangle ABX\triangle ABX is greater than 25 is 16\boxed{\frac{1}{6}}.

Would you like further details or have any other questions?


Here are 5 related questions you may find interesting:

  1. How does the random selection of point XX inside ABC\triangle ABC influence the area of ABX\triangle ABX?
  2. Can you calculate the probability that ABX\triangle ABX has an area less than 15?
  3. How would the solution change if triangle ABCABC was not a right triangle?
  4. What if the area of triangle ABXABX had to be exactly 25? What would the probability be then?
  5. How can we generalize this problem to triangles with different base and height dimensions?

Tip: In geometric probability, the area ratios often give the simplest way to calculate probabilities when dealing with random points within a region.

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Math Problem Analysis

Mathematical Concepts

Geometry
Probability
Area of Triangle
Proportion

Formulas

Area of triangle = 1/2 * base * height
Proportion relation for area fractions

Theorems

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Suitable Grade Level

High School