11 Angles

There are 360\textdegree (degrees) in a complete revolution (i.e. a full circle)

There are 180\textdegree in half a revolution (i.e. a straight angle, aka straight angle)

There are 90\textdegree in a quarter revolution (i.e. 2 lines perpendicular, aka a right angle). This has a special symbol:

Angles between 0\textdegree and 90\textdegree are called acute angles.

Angles between 90\textdegree and 180\textdegree are called obtuse angles.

Angles between 180\textdegree and 360\textdegree are called reflex angles.

When determining whether an angle is acute/obtuse/reflex, the position of the angle isn’t important, only the size. It does depend on which angle you’re talking about though, because the opposite side of an acute angle is going to be a reflex angle!


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