Angle

• What is an angle defined as in geometry?

  An angle is a figure formed by two rays with a common endpoint.
• How are angles classified?

  Angles are classified according to their measures.
• What is the measure of a straight angle?

  A straight angle measures $180^\circ$.
• What is the measure of a right angle?

  A right angle measures $90^\circ$.
• What is the measure of an acute angle?

  An acute angle measures less than $90^\circ$.
• What is the measure of an obtuse angle?

  An obtuse angle measures more than $90^\circ$ but less than $180^\circ$.
• What is the measure of a reflex angle?


  A reflex angle measures more than $180^\circ$ but less than $360^\circ$.
• What is a supplementary angle?

  Supplementary angles sum up to $180^\circ$.
• What is a complementary angle?


  Complementary angles sum up to $90^\circ$.
• What are the classifications of angles based on their measures?

  • Acute angle: less than $90^\circ$
  • Right angle: exactly $90^\circ$
  • Obtuse angle: more than $90^\circ$ but less than $180^\circ$
  • Straight angle: exactly $180^\circ$
  • Reflex angle: more than $180^\circ$ but less than $360^\circ$