Chapter 28: Problem 19
The sides of a triangle are \(3 x+4 y, 4 x+3 y\) and \(5 x+5 y\) where \(x\), \(y>0\) then the triangle is (a) right angled (b) obtuse angled (c) equilateral (d) none of these
Short Answer
Expert verified
The triangle is obtuse-angled.
Step by step solution
01
Understand the Problem
We are given three sides of a triangle: \(3x + 4y\), \(4x + 3y\), and \(5x + 5y\). We need to determine the type of triangle based on these side lengths. We have options: right-angled, obtuse-angled, equilateral, or none of these.
02
Analyze Side Lengths for Equality
An equilateral triangle has all sides equal. Compare the given side lengths:1. Check if \(3x + 4y = 4x + 3y\)2. Check if \(4x + 3y = 5x + 5y\)3. Check if \(3x + 4y = 5x + 5y\)Since none of these equalities hold, the triangle is not equilateral.
03
Check for Right Angle Using Pythagoras Theorem
In a right-angled triangle, the square of the longest side should equal the sum of the squares of the other two. Identify the longest side, which is \(5x + 5y\). Verify:\((5x + 5y)^2 = (3x + 4y)^2 + (4x + 3y)^2\)Calculate both sides and compare:\[(25x^2 + 50xy + 25y^2) eq (9x^2 + 24xy + 16y^2 + 16x^2 + 24xy + 9y^2)\]The equality doesn't hold, so the triangle is not right-angled.
04
Check for Obtuse Angle Using Extended Pythagorean Theorem
For an obtuse-angled triangle, one side squared should be greater than the sum of the squares of the other two sides for the longest side:\((5x + 5y)^2 > (3x + 4y)^2 + (4x + 3y)^2\)Simplifying leads to:\(25x^2 + 50xy + 25y^2 > 25x^2 + 48xy + 25y^2\)This inequality holds, indicating that the triangle is obtuse-angled.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Right-Angled Triangle
A right-angled triangle is one that has one angle measuring precisely 90 degrees. This triangle has some fascinating properties:
Understanding the structure of right-angled triangles is crucial for solving many geometrical problems, as they simplify calculations using their specific properties.
- The side opposite the right angle is known as the hypotenuse, and it is the longest side.
- Pythagoras' Theorem applies: in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. Mathematically, this is written as: \(c^2 = a^2 + b^2\).
Understanding the structure of right-angled triangles is crucial for solving many geometrical problems, as they simplify calculations using their specific properties.
Obtuse-Angled Triangle
An obtuse-angled triangle has one angle that is greater than 90 degrees. These triangles have some distinct properties:
Understanding this concept helps students identify obtuse triangles quickly, especially when they are involved in complex geometric calculations or proofs.
- In an obtuse triangle, the side opposite the obtuse angle is the longest.
- The square of this longest side is greater than the sum of the squares of the other two sides, as per the Extended Pythagorean Theorem. This can be expressed as: \(c^2 > a^2 + b^2\).
Understanding this concept helps students identify obtuse triangles quickly, especially when they are involved in complex geometric calculations or proofs.
Equilateral Triangle
An equilateral triangle is a triangle where all three sides are of equal length, and each angle measures 60 degrees. This symmetry gives the equilateral triangle unique characteristics:
Recognizing the distinct properties of equilateral triangles is vital for understanding concepts of symmetry and congruence in geometry.
- All sides are equal, typically written formulaically as \(a = b = c\).
- It is perfectly balanced, with each angle being equal, resulting in a high level of symmetry.
Recognizing the distinct properties of equilateral triangles is vital for understanding concepts of symmetry and congruence in geometry.