Definition

1. Noun:
   • An angle between 90 and 180 degrees: An "obtuse angle" is a specific geometric figure formed by two rays that share a common endpoint (vertex), where the measure of the opening between them is greater than 90 degrees but less than 180 degrees.

Usage

• The term "obtuse angle" is used in geometry, mathematics, engineering, and design to classify and describe angles. It is the opposite of an acute angle (less than 90 degrees) and distinct from a right angle (exactly 90 degrees) and a straight angle (exactly 180 degrees).
• It is typically used as a countable noun (e.g., , ).

Examples

• Noun:
  • The triangle contains one obtuse angle and two acute angles.
  • When the hands of a clock show 4:10, they form an obtuse angle.
  • A parallelogram can have two obtuse angles.

Advanced Usage

• "To be obtuse" (adjective): While the adjective "obtuse" can describe an angle, it has a separate, figurative meaning describing a person who is slow to understand or perceive something. This is a distinct usage from the noun phrase "obtuse angle."
  • His obtuse remarks failed to grasp the complexity of the issue. (Here, 'obtuse' is an adjective meaning 'dull-witted,' not a reference to the angle.)

Variants and Related Words

• Obtuse (adjective): Describing an angle that is between 90 and 180 degrees.
  • An obtuse triangle has one obtuse angle.
• Acute angle (noun): An angle less than 90 degrees.
• Right angle (noun): An angle exactly equal to 90 degrees.
• Reflex angle (noun): An angle greater than 180 degrees but less than 360 degrees.

Synonyms

• There are no direct single-word synonyms for the noun phrase "obtuse angle." It is a precise technical term. It can be described periphrastically as .

Related Phrases

• "Measure an obtuse angle": To determine the degree measure of such an angle.
  • Use a protractor to measure the obtuse angle accurately.
• "Construct an obtuse angle": To draw an angle of this type using geometric tools.
  • The first step is to construct an obtuse angle of 120 degrees.

Noun

1. an angle between 90 and 180 degrees