# Chapter 2 - Geometric Figures

Geometric Figures

In the Geometric Figures Unit, students will expand on their understanding of basic geometric concepts by investigating shapes that occur often in everyday life: polygons, lines, and circles. Students classify triangles and other polygons, and they connect geometry to algebra by relating parallel and p erpendicular to the concept of slope. They explore angles and arcs of a circle and apply those ideas to circle graphs. They learn about congruence and similarity.

All of the exterior angles in a polygon add up to 360 degrees. To find the exterior angle, you can add the 2 remote interior angles. As shown above, the 2 remote interior angles are the 2 angles that are opposite of the exterior angle. In a regular polygon, you can use the formula in the formulas link below to find the angle measures for each angle. They should all be equal since its a regular polygon.

Triangles can be classified in deifferent ways. In the Geometric Flipchart
below, you can learn different ways to classify triangles. They all have
different properties. As shown above, all triangles are 3 sided enclosed
figures. All triangle angle's add up to 180 degrees.

Regular Polygons

The sum of the measures of the interior angles of an n-gon is (n-2)180.

The sum of the measures of the exterior angles of a polygon, one at each vertex, is 360.

Parallel lines are lines that never touch. Parallel lines can run in any direction as long as the two lines do not intersect. The opposite of parallel lines are perpendicular lines. Perpendicular lines are lines that intersect forming a 4 right angles. Both lines can be used on a coordinate plane using the slope formula. The slope in the formula must be the same for 2 lines to be parallel. For perpendicular lines, the slope in the formula must be the opposite and the reciprocal for the 2 lines to be perpendicular.

DEFINITIONS
The link about displays all the definitions that appear throughout the chapter

The postulate link displays all the important postulates and theorms

The formulas link is unclosed with the formula needed to complete different equations