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Right, Acute & Obtuse Angles

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Basics on the topic Right, Acute & Obtuse Angles

How do we know whether an angle is acute, right, obtuse or reflex? Learn here about the different types of angles.

2 comments
2 comments
  1. I'm having fun

    From Kanni, 9 months ago
  2. It reminds me of yoga

    From Kanni, 9 months ago

Right, Acute & Obtuse Angles exercise

Would you like to apply the knowledge you’ve learnt? You can review and practice it with the tasks for the video Right, Acute & Obtuse Angles.
  • Identify the types of angles.

    Hints

    A right angle is the most common angle and forms a perfect square at the corner of the arc.

    A complete circle is 360°.

    An acute angle is less than 90°.

    An obtuse angle is more than 90° and less than 180°.

    Solution
    • A straight angle or line is 180°.
    • A reflex angle is more than 180° but less than 360°.
    • A right angle is 90°.
    • A complete angle is 360°, or a full circle.
  • Define the terms.

    Hints

    Most angles have arcs.

    Remember, an angle less than a right angle is an acute angle.

    A vertex is where two or more lines meet.

    Solution
    • Obtuse angles have a large arc, more than 90° and less than 180°.
    • Acute angles have a small arc less than 90°.
    • The vertex is the point where two rays meet to form an angle.
    • Right angles measure exactly 90°.
  • Sort different angles.

    Hints

    An acute angle is less than 90°.

    An obtuse angle is more than 90° and less than 180°.

    Two choicies are acute angles, two choices are obtuse angles and one choice is a right angle.

    Solution

    OBTUSE ANGLES are more than 90° and less than 180°

    • 120°
    • 150°
    ACUTE ANGLES are less than 90°
    • 60°
    • 45°
    A RIGHT ANGLE is 90°

  • Identify the types of angles.

    Hints

    A complete circle is 360°.

    An acute angle is less than 90°.

    A reflex angle is more than 180° but less than 360°.

    A straight angle is also known as a line.

    Solution

    REFLEX ANGLES are more than 180° and less than 360°

    • 215°
    • 197°
    ACUTE ANGLES are less than 90°
    • 45°
    A STRAIGHT ANGLE is 180°
    A COMPLETE ANGLE is 360°, or a full circle

  • Label the angle.

    Hints

    An acute angle has a small arc of less than 90°.

    An obtuse angle has a large arc of more than than 90° and less than 180°.

    A complete angle is 360°

    Solution

    A right angle is the most common angle and forms a perfect square at the corner of the arc. Its arc is 90°

  • Name and define the angles.

    Hints

    This is an obtuse angle because it is greater than 90° and less than 180°.

    A straight angle is also known as a line.

    A complete circle is 360°.

    Solution
    • A right angle is 90°
    • An acute angle is less than 90°
    • An obtuse angle is greater than 90° and less than 180°
    • A straight angle is 180°
    • A reflex angle is greater than 180° and less than 360°
    • A complete angle is 360°