Obtuse Angle

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Definition of Obtuse Angle

Any angle greater than 90° and smaller than 180° is called an Obtuse Angle.

More About Obtuse Angle

  • An angle of 90° is called a right angle.
  • An angle of 180° is called a straight angle.

Example of Obtuse Angle

    The angle shown in the figure is greater than 90° but smaller than 180°, so it is an obtuse angle.

Video Examples: Acute and Obtuse Angles in Geometry


Solved Example on Obtuse Angle

Ques: Identify the obtuse angle in the given triangle.

    Choices:
    A. ∠ACB
    B. ∠ABC
    C. ∠BAC
    D. ∠CAB
    Correct Answer: B

Solution:

    Step 1:An angle greater than a right angle and less than a straight angle (> 90° and < 180°) is called an obtuse angle.
    Step 2: In the given figure, ∠A and ∠C are acute angles and ∠B is an obtuse angle.
    Step 3: So, ∠ABC is an obtuse angle.

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