Measure the Angles of a Polygon 

To find the measure of all the angles of any polygon: 

• Divide the polygon into triangles
• Multiply the number of triangles by 180°.

Measure of angles = 4 triangles * 180° = 720°. 

To find the measure of  an angle of a regular polygon: 

• Divide the sum of the measure of all the angles by the number of angles.

• Multiply (the number of angles – 2) by 180°.
• Then divide by the number of angles.

For a regular octagon:  

Step 1: (8 angles -2) * 180° = 6 * 180° = 1,080° 

Step 2: 1,080° ÷ 8 = 135°