Triangle Classification: Identifying a Right Triangle with 90-Degree Angle

Triangle Classification with Angle Measurements

What kid of triangle is given in the drawing?

90°90°90°AAABBBCCC

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Identify what type of triangle it is
00:03 The triangle has a right angle according to the given information
00:06 Therefore, the triangle is right-angled, and this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

What kid of triangle is given in the drawing?

90°90°90°AAABBBCCC

2

Step-by-step solution

The measure of angle C is 90°, therefore it is a right angle.

If one of the angles of the triangle is right, it is a right triangle.

3

Final Answer

Right triangle

Key Points to Remember

Essential concepts to master this topic
  • Right Triangle Rule: Any triangle with a 90° angle is a right triangle
  • Angle Identification: Look for the square symbol marking the 90° angle
  • Verification: Check that one angle equals exactly 90 degrees ✓

Common Mistakes

Avoid these frequent errors
  • Confusing triangle types based on side lengths only
    Don't classify triangles by just looking at equal sides = missing the angle classification! Side lengths tell you if it's isosceles or scalene, but angles determine if it's right, acute, or obtuse. Always check the angle measures first when classifying triangles.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

How do I know it's a right triangle and not just isosceles?

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Look for the 90° angle marker in the diagram! The small square symbol at angle C shows it's exactly 90 degrees. Even if two sides are equal (making it also isosceles), the 90° angle makes it a right triangle first and foremost.

What if a triangle has both equal sides and a 90° angle?

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Great observation! A triangle can be both right AND isosceles. But when asked 'what kind of triangle,' the 90° angle is the most important feature, so the answer is right triangle.

How can I remember the difference between triangle types?

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By angles:

  • Right triangle = has one 90° angle
  • Acute triangle = all angles less than 90°
  • Obtuse triangle = has one angle greater than 90°

Does the position of the right angle matter?

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No! A right triangle is a right triangle no matter where the 90° angle is located. Whether it's at the bottom, top, or side doesn't change the classification.

What does the small square symbol mean?

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The small square drawn at an angle is the universal symbol for a right angle (90°). Whenever you see this square, you know that angle measures exactly 90 degrees!

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