Angles around a point.

​1. Angles around a point total 360 degrees.

​2. Angles on a line total 180 degrees.

​3. Vertically opposite angles are equal.

​Parallel line angles

​1. Corresponding angles are equal.

​2. Alternate angles are equal.

​3. Co-interior angles add up to 180 degrees.

​Interior angles in polygons

• ​Regular shapes have all sides the same lengths and all angles equal.

• Angles in a triangle add up to 180 degrees.

• Angles in a quadrilateral add up to 360 degrees.

• To calculate the sum of the interior angles in a N sided polygon use 180x(n-2).

• To calculate the size of one angle in a regular n sided polygon divide your result by n. ​

​Finding missing angles

​1. To calculate missing angles, use the previous angle rules and subtract the known angles from the sum of the angles.

​2. You can use algebra for missing angles.