Triangle Side Analysis: Determining if X+1 Creates a Scalene Triangle

Triangle Classification with Side Length Comparison

Given the values of the sides of a triangle, is it a triangle with different sides?

XXXAAABBBCCCX+1X+1

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Step-by-step video solution

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00:00 Determine whether the triangle is scalene
00:03 According to the given side lengths, the triangle is isosceles
00:07 This is the solution

Step-by-step written solution

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1

Understand the problem

Given the values of the sides of a triangle, is it a triangle with different sides?

XXXAAABBBCCCX+1X+1

2

Step-by-step solution

To determine if the triangle with sides XX, X+1X+1, X+1X+1 is a scalene triangle, we need to confirm that all sides are of different lengths.

Using the triangle inequality theorem:

  • X+(X+1)>(X+1)2X+1>X+1 X + (X + 1) > (X + 1) \rightarrow 2X + 1 > X + 1, which simplifies to X>0X > 0.
  • X+(X+1)>(X+1)2X+1>X+1 X + (X + 1) > (X + 1) \rightarrow 2X + 1 > X + 1, which also simplifies to X>0X > 0.
  • (X+1)+(X+1)>X2X+2>X (X + 1) + (X + 1) > X \rightarrow 2X + 2 > X, which simplifies to X>2X > -2.

All these conditions are satisfied if XX is a positive number. Next, check if all sides differ:

  • XX and X+1X+1 are different, by definition.
  • However, the two longer sides are both X+1X+1, meaning not all sides are different.

The triangle is thus not scalene, as it does not have all sides of different lengths.

Therefore, the correct answer is No.

3

Final Answer

No

Key Points to Remember

Essential concepts to master this topic
  • Scalene Definition: All three sides must have different lengths
  • Analysis Method: Compare X, X+1, X+1 to identify equal sides
  • Verification: Two sides equal X+1 means not scalene ✓

Common Mistakes

Avoid these frequent errors
  • Assuming triangle inequality automatically means scalene
    Don't think triangle inequality = scalene triangle! Triangle inequality only proves it's a valid triangle, not that all sides differ. Always check if any two sides are equal after confirming it's a triangle.

Practice Quiz

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Is the triangle in the drawing a right triangle?

FAQ

Everything you need to know about this question

What's the difference between scalene and other triangle types?

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Scalene: All three sides different lengths
Isosceles: Exactly two sides equal
Equilateral: All three sides equal

This triangle has sides X, X+1, X+1 - that's isosceles, not scalene!

Do I need to check the triangle inequality first?

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Yes! Always verify it's a valid triangle using triangle inequality (sum of any two sides > third side) before classifying it as scalene, isosceles, or equilateral.

How do I quickly identify if sides are different?

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List all three sides and compare them directly:

  • Side 1: X X
  • Side 2: X+1 X+1
  • Side 3: X+1 X+1

Since sides 2 and 3 are equal, it's not scalene.

Can X be any positive number here?

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Yes! For any positive value of X, you get a valid triangle with sides X, X+1, X+1. But regardless of X's value, it will always be isosceles (not scalene) because two sides are always equal.

What if the question asked about isosceles instead?

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Then the answer would be Yes! This triangle with sides X, X+1, X+1 is definitely isosceles because exactly two sides (both X+1) are equal.

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