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Lesson 2: Angle introduction

# Drawing acute, right and obtuse angles

Learn how to draw acute, right, and obtuse angles with given points. Created by Sal Khan.

## Want to join the conversation?

• How many times in life do you think we use angles?
• Us humans use angles lots and lots of times in our times. For example, if you have a job, that has to do with building or creating, (a engineer) you would use angles almost every day of your life. You need to know how much degrees to build a corner or wall. Angles is a really important part to learn in our lives.
• i wonder if there is fraction angles like: 5 and 2 over 7 or something like that
• Radians are often measured with fractions. For example: pi / 2 = 90°
(1 vote)
• why do we have to know angles
• in order to define and study polygons such quadrilaterals and use in our everyday life.
• So Obtuse Is more than 90, Acute is less than 90 and right is 90? I'm Not Sure about The Right One, Please tell me!
• Yeah, obtuse is is more than 90, acute is less than 90, right is 90, straight is 180, and reflex is more than 180.
• What are the exact degree's for all angles?
• acute angles are between 0 and 90, right angles are 90, obtuse angles are between 90 and 180, straight angles[straight line] are 180, reflex angles are between 180 and 360, and complete angles are 360 degrees.
(1 vote)
• How many types of angles are there?
• 4:acute,obtuse,right angle and reflex.A acute angle is less than 90 degrees,a right angles is 90 degrees,a obtuse angle is 90-180 degrees and a reflex is more than 180 degrees.
• what is a acute angle again
• an angle less than 90degrees
you can use this trick to remember
a"cute": cute things are normally small
A"cute" angle is small or lesser than 90 degrees.
:D
i hope this helped
^U^
• what is the difference between straight angle and complete angle?
• Straight angle creates a line while a complete angle only creates a single ray. Or in angles 180° is straight and 360° complete.

Complete is basically like a 0° angle, in the sense there won't be a gap, between the two lines.

Hope this helped.