Lesson 1: Angles - Types of Angles

   Constructing Knowledge

Angles can be classified based on the degree.

You may recall using a protractor to measure angles in previous math courses. There are 360° in a full circle, and most protractors you see are semi circles, which measure up to 180°.


Types of Angles


Type of Angle description referent picture
Right angle
  • Measures 90°
  • Looks like an "L" shape made with your finger and thumb
Straight angle
  • Measures 180°
  • Looks like a straight line
Acute angle
  • Any angle that is smaller than 90°
  • All angles between the fingers on your hand
Obtuse angle
  • More than 90°
  • Less than 180°
Reflex angle
  • Measures more than 180°
  • Less than 360°

EXAMPLE

Classify the following angles:






Solution


Question angle angle type
a. acute angle
b. reflex angle
c. right angle
d. straight angle
e. obtuse angle


Now, it is your turn! Complete the questions in your Chapter 6, Lesson 1 Practice Makes Perfect that refer to Types of Angles.



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