# Basic Geometry

### Example 1

What is the sum of the angles in a dodecagon? | A dodecagon has 12 sides, so . |

### Example 2

What is the measure of each angle in a regular nonagon? | A nonagon has 9 sides. Using our formula, . |

### Example 3

Find the missing angle. | A triangle has 180°. If we add the measures of angles I and J and subtract from 180, we get: |

### Example 4

Find the measurement of angle Q | This is a hexagon. The total number of degrees equals: |

### Example 5

Find the missing angles in this isosceles trapezoid. | Since this is an isosceles trapezoid, angles I and L are congruent. In addition, angles J and K are congruent, so |