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### Course: Geometry (all content)>Unit 2

Lesson 8: Sal's old angle videos

# Intro to angles (old)

What an angle is. Angles in a circle. Complementary and supplementary angles. Created by Sal Khan.

## Want to join the conversation?

• are there angles less than 0?
• Yes. -270 degrees is equal to 90 degrees, therefore they do exist. Just not in "basic" geometry.
• is there any such thing as a reflex angle
• Reflex angles do exist! They are between 181 degrees to 360 degrees.
• can a obtuse angle be more than 180 degrees
• No. Then it would turn into a reflex angle.
• What are angles more than 180° called?
• Reflex angles.
• whats suplamentary angles
• Supplementary angles are angles that add to 180 degrees.
• If you have a 360 degrees angle, would the center of the circle be the vertex ?
• yes, the center of the circle would be the vertex
• Why do you have to measure the inner part of the cirlce, why not the wide outside?
• the circle?? i think you meant the angle.
• Did any one make up angles or it just came about?
(1 vote)
• They occur in nature and so somebody decided to create a way to measure them either through radians or degrees