Interior angles of a Triangle

The angles inside a polygon are

called interior angles.

When the

sides of a polygon are extended,

other angles are formed. The angles

outside the polygon that are

adjacent to the interior angles

are called exterior angles.

The sum of the interior angle

measures of a triangle is 180°.

x + y + z = 180

The measure of an exterior angle

of a triangle is equal to the sum

of the measures of the two

nonadjacent interior angles.

z = x + y