Geometric Language How to Speak

Plane A plane is an endless flat surface. We can only see part of the plane since it goes on forever. The top of your table, a bulletin board and the chalk board are examples of planes.

Point A point is an exact location in space. Points are usually named with a capital letter. A thumb tack is a good way to imagine a point on a plane.. M Call this M or Point M

Line A line is a straight path of points that goes on forever in both directions. The arrows on the line help us remember that we are only looking at a part of the line. Lines are usually named using two points... PQ “Line PQ” or PQ or “Line QP” or QP

Line Segment A line segment is part of a line. A segment has a specific starting point and ending point. The midpoint is halfway between the end points... X Y “Line segment XY” or XY, or “Line segment YX” or YX. Midpoint

Ray A ray is part of a line. It has one end point and extends forever in one direction. Think of a ray as a flashlight. It starts in a specific spot and shines out to light your straight path.. GH. “Ray GH” or GH, NOT “Ray HG”! Why do you think that is?

Parallel Lines Parallel lines stay the same distance apart and never cross..... “Line AB is parallel to line CD” or AB || CD D C AB || means “parallel to” Think of parallel lines as the lanes on the highway, they are always next to each other and will never cross.

Intersecting Lines Intersecting lines pass through the same point. In other words, they cross. Think of intersecting lines as roads that cross J K L M LK intersects JM S

Perpendicular Lines Perpendicular lines are lines that intersect and make square corners. These square corners are called “right angles.” Think of these as roads that cross in the city. This little square tells you the lines are perpendicular..... A M S F “Line FM is perpendicular to line SA” FM | SA

Try It! G F E D C B A J H Look at the geometric figure. Can you find A line? A ray? A pair of intersecting lines? A pair of perpendicular lines? A point? A plane?

What geometric figures do you see in the photograph?

Congratulations! Now you speak a new language – Geometric Language! Now, can you tell me where I can find the rectangular opening in the vertical plane that makes up the side of this room?