why is the isosceles triangle and the equilateral both classified as each other

because an equilateral triangle is all equill sides and an isosceles triangle is two or more equill sides

Is their any more triangle practices?

No. You will have to do them over if you want extra practice.

i got my one right but it said i got it worng

I... I think that means you got it wrong, but you don't understand. You might want to check your answer or ask someone else to explain it to you.

um whenever i double tap a question it ameatiatily says its wrong

dont double tap just tap and check

I don’t understand why an equilateral triangle is constantly being defined as and Isosceles triangle.

An equilateral triangle has 3 equal length sides. An isosceles triangle has at least 2 sides of the same length. Thus all equilateral triangles are also isosceles.

Why do all sides measurements in a triangle have to equal 180

Nice question! I think you meant to ask why all the angle measurements in a triangle add to 180 degrees. The side measurements can add up to anything. There is a geometry proof of the fact that the angles in a triangle must add to 180 degrees. Draw a triangle with vertices at points A, B, and C, and draw a line through vertex C that is parallel to side AB. This diagram forms three non-overlapping angles at vertex C. Two of the angles are just outside the triangle and one of the angles is angle C inside the triangle. These three non-overlapping angles formed at vertex C clearly add to 180 degrees (because together, they form a semicircle). Because alternate interior angles are congruent when parallel lines are cut by another line (transversal), angle A in the triangle is congruent to one of the angles at C outside the triangle, and angle B in the triangle is congruent to the other angle at C outside the triangle. It follows from these last two statements that angles A, B, and C in the triangle add to 180 degrees. Have a blessed, wonderful day!

Main content

Course: 4th grade > Unit 11

Lesson 4: Classifying triangles

Types of triangles review

Google Classroom

Review ways to classify triangles based on their sides lengths and angles. Practice classifying triangles.

Classifying triangles by their angles

Acute triangles

acute

triangle has

3 angles that

each measure less than 90^{\circ}

. Below are examples of

acute triangles

Right triangles

right

triangle has

1 angle that measures 90^{\circ}

and

2

acute angles. Below are examples of

right triangles

Obtuse triangles

obtuse

triangle has

one angle that measures

more than 90^{\circ}

and

2

acute angles. Below are examples of

obtuse triangles

Want to learn more about classifying triangles? Check out this video.

Problem 1A

Classify $△ P Q R$ ‍ by its angles.

Want to try more problems like this? Check out this exercise

Classifying triangles by their side lengths

Equilateral triangles

equilateral

triangle has

three equal sides

. Below are examples of

equilateral

triangles.

Isosceles triangles

isosceles

triangle has

\underset{―}{at least}

two equal sides

. Below are examples of

isosceles

triangles.

Scalene triangles

scalene

triangle has

no equal sides

. Below are examples of

scalene

triangles.

Problem 2A

Classify $△ P Q R$ ‍ by its sides.

Want to try more problems like this? Check out this exercise.

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TJ
Posted 6 years ago. Direct link to TJ's post “Why can't I go back to se...”
Why can't I go back to selecting? I got a wrong and I can't go back
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- 28fcoraggio
  Posted 2 years ago. Direct link to 28fcoraggio's post “It just won't let you.”
  It just won't let you.
  Comment on 28fcoraggio's post “It just won't let you.”
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kezia bukuru
Posted 5 years ago. Direct link to kezia bukuru's post “why is the isosceles tria...”
why is the isosceles triangle and the equilateral both classified as each other
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(48 votes)
Answer
- Ryan Gati
  Posted 4 years ago. Direct link to Ryan Gati's post “because an equilateral tr...”
  because an equilateral triangle is all equill sides and an isosceles triangle is two or more equill sides
  Comment on Ryan Gati's post “because an equilateral tr...”
  (18 votes)
Kumo yamashita
Posted 7 years ago. Direct link to Kumo yamashita's post “Is their any more triangl...”
Is their any more triangle practices?
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(23 votes)
Answer
- naokantey
  Posted 7 years ago. Direct link to naokantey's post “No. You will have to do t...”
  No. You will have to do them over if you want extra practice.
  Comment on naokantey's post “No. You will have to do t...”
  (12 votes)
Noah Remetan
Posted 4 years ago. Direct link to Noah Remetan's post “Why are triangles used in...”
Why are triangles used in math?
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(16 votes)
Answer
- ethan.smidt
  Posted a year ago. Direct link to ethan.smidt's post “it is because it uses geo...”
  it is because it uses geometry
  Comment on ethan.smidt's post “it is because it uses geo...”
  (9 votes)
Nyaruyoma
Posted 5 years ago. Direct link to Nyaruyoma's post “I don’t understand why an...”
I don’t understand why an equilateral triangle is constantly being defined as and Isosceles triangle.
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(8 votes)
Answer
- Nights Dawn
  Posted 4 years ago. Direct link to Nights Dawn's post “An equilateral triangle h...”
  An equilateral triangle has 3 equal length sides. An isosceles triangle has at least 2 sides of the same length. Thus all equilateral triangles are also isosceles.
  Comment on Nights Dawn's post “An equilateral triangle h...”
  (30 votes)
julia beltran
Posted 6 years ago. Direct link to julia beltran's post “if all of the angels are ...”
if all of the angels are acute but lenghths are different what is that?
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(6 votes)
Answer
- 😇Diego😈
  Posted a year ago. Direct link to 😇Diego😈's post “its scalene”
  its scalene
  Comment on 😇Diego😈's post “its scalene”
  (11 votes)
middleton.daveyon
Posted 4 years ago. Direct link to middleton.daveyon's post “i got my one right but it...”
i got my one right but it said i got it worng
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(12 votes)
Answer
- daisyoverhill5
  Posted 10 months ago. Direct link to daisyoverhill5's post “I... I think that means y...”
  I... I think that means you got it wrong, but you don't understand. You might want to check your answer or ask someone else to explain it to you.
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  (4 votes)
Emma
Posted 3 years ago. Direct link to Emma's post “um whenever i double tap ...”
um whenever i double tap a question it ameatiatily says its wrong
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(10 votes)
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- 😇Diego😈
  Posted a year ago. Direct link to 😇Diego😈's post “dont double tap just tap ...”
  dont double tap just tap and check
  Comment on 😇Diego😈's post “dont double tap just tap ...”
  (6 votes)
annalies.1913965
Posted 4 years ago. Direct link to annalies.1913965's post “it said that a acute was ...”
it said that a acute was like all the sides lower then 90* but the last one was over 90*
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(7 votes)
Answer
- 😇Diego😈
  Posted a year ago. Direct link to 😇Diego😈's post “then it was obtuse”
  then it was obtuse
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  (4 votes)
Vish Dilipan
Posted 6 years ago. Direct link to Vish Dilipan's post “Why do all sides measurem...”
Why do all sides measurements in a triangle have to equal 180
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(3 votes)
Answer
- Ian Pulizzotto
  Posted 6 years ago. Direct link to Ian Pulizzotto's post “Nice question! I think y...”
  Nice question! I think you meant to ask why all the angle measurements in a triangle add to 180 degrees. The side measurements can add up to anything.
  
  There is a geometry proof of the fact that the angles in a triangle must add to 180 degrees.
  
  Draw a triangle with vertices at points A, B, and C, and draw a line through vertex C that is parallel to side AB. This diagram forms three non-overlapping angles at vertex C. Two of the angles are just outside the triangle and one of the angles is angle C inside the triangle.
  
  These three non-overlapping angles formed at vertex C clearly add to 180 degrees (because together, they form a semicircle).
  
  Because alternate interior angles are congruent when parallel lines are cut by another line (transversal), angle A in the triangle is congruent to one of the angles at C outside the triangle, and angle B in the triangle is congruent to the other angle at C outside the triangle.
  
  It follows from these last two statements that angles A, B, and C in the triangle add to 180 degrees.
  
  Have a blessed, wonderful day!
  Comment on Ian Pulizzotto's post “Nice question! I think y...”
  (11 votes)