angles

A vertex is a point where two lines meet or two line segments meet.

Angles are formed when lines intersect. 

An angle is the amount of rotation between two lines (or line segments) that meet at a single vertex.

An angle is measured in degrees and has a symbol °.

An angle is named using three letters - the three points that create the angle, with the vertex point in the middle.

We use a 'hat' above the vertex (Point B) OR the angle sign out front.

An interior angle is an angle inside a polygon.

An exterior angle is an angle outside a polygon.

Note #1 we extend a side to create an exterior angle, it is not the entire angle.

Note #2 an interior angle and exterior angle are on a straight line, hence sum to 180 degrees.

Note #3 when we are using all exterior angles, we must 'extend the sides' in the same orientation.