Angles and their Classification

When lines intersect, angles are formed. The endpoint shared by the two sides is called the vertex

Angles can be named in a variety of ways:

a) When there is no chance of confusion, an angle can be named with only one letter, the letter of its vertex

b) An angle can also be named with three letters, using a point from one side, the vertex, and a point from the other side. The vertex must be in the middle

c) The angles can also be named with a number or letter in the interior of the angle

The square angles formed by two lines are right angles. A right angle measures 90^o

A straight angle is an angle on a straight line. It measures exactly 180°

An acute angle measures less than 90° (less than a right angle)

An obtuse angle measures more than 90° and less than 180°(more than a right angle, but less than a straight angle)

The square angles formed by two lines are right angles

A straight angle is an angle on a straight line. It measures exactly 180°

An obtuse angle measures more than 90° and less than 180°(more than a right angle, but less than a straight line)

An acute angle measures less than 90^o (less than a right angle)