Triangle Classification: Is a 4-4-5 Triangle Scalene?

Q: What's the difference between scalene, isosceles, and equilateral triangles?

Scalene: All three sides are different lengthsIsosceles: Exactly two sides are equalEquilateral: All three sides are equal

Q: Why isn't a 4-4-5 triangle scalene if it has different sides?

A triangle is only scalene if all three sides are different. Since this triangle has two sides of length 4, it's isosceles, not scalene.

Q: How do I quickly identify triangle types by looking at side lengths?

Count how many sides are the same length0 pairs equal = scalene1 pair equal = isoscelesAll 3 equal = equilateral

Q: Can a triangle be both isosceles and scalene?

No! These are mutually exclusive categories. A triangle can only be one type: scalene, isosceles, or equilateral. Think of them as three separate boxes - a triangle fits in exactly one box.

Q: What if I see a triangle with sides like 3-3-3?

That's an equilateral triangle because all three sides are equal. Remember: equilateral is a special case of isosceles (since it has at least two equal sides).

Triangle Classification with Isosceles Properties

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

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

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

Follow each step carefully to understand the complete solution

Understand the problem

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

Step-by-step solution

The triangle with sides 4, 4, and 5 is not a triangle with different sides. Therefore, the answer is No.

Final Answer

Key Points to Remember

Essential concepts to master this topic

Definition: Scalene triangles have three different side lengths
Method: Compare sides: 4 = 4 ≠ 5 shows two equal sides
Check: Two equal sides means isosceles, not scalene triangle ✓

Common Mistakes

Avoid these frequent errors

Confusing scalene and isosceles definitions
Don't think scalene means 'any triangle with at least one different side' = wrong classification! This confuses the three types. Always remember: scalene needs ALL three sides different, isosceles has exactly two equal sides, equilateral has all three equal.

Practice Quiz

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In a right triangle, the side opposite the right angle is called....?

FAQ

Everything you need to know about this question

What's the difference between scalene, isosceles, and equilateral triangles?

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

Why isn't a 4-4-5 triangle scalene if it has different sides?

A triangle is only scalene if all three sides are different. Since this triangle has two sides of length 4, it's isosceles, not scalene.

How do I quickly identify triangle types by looking at side lengths?

Count how many sides are the same length
0 pairs equal = scalene
1 pair equal = isosceles
All 3 equal = equilateral

Can a triangle be both isosceles and scalene?

No! These are mutually exclusive categories. A triangle can only be one type: scalene, isosceles, or equilateral. Think of them as three separate boxes - a triangle fits in exactly one box.

What if I see a triangle with sides like 3-3-3?

That's an equilateral triangle because all three sides are equal. Remember: equilateral is a special case of isosceles (since it has at least two equal sides).

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