Basic Shapes at a Glance

This is where it all begins: basic shapes, lines, and angles.

Read on and let us take you on a magical geometry tour...

Name	Description	Example
Point	A single location. Usually drawn as a dot. It is "dimensionless". Labeled as Point P. You used these when playing Connect the Dots.
Line	A straight path passing through at least two points. Extends in both directions forever. Labeled as Think of this as a highway that never ends.
Line Segment	A portion of a line. It has limits at each end. Labeled as When writing the length of leave off the line like this: CD = length You've drawn these since you were 1½!
Ray	A straight path with one terminal point and extending indefinitely in the other direction. Labeled as (Make sure to start with the terminal point and extend past the other point.) Picture the sun as a terminal point and its rays extending indefinitely into space.
Plane	A flat surface without boundaries. Labeled by naming three nonlinear points on the plane, Plane GHI. It's like a piece of paper that extends in every direction forever.
Parallel Lines	Lines that lie on the same plane and never intersect. Labeled as Look at a piece of lined paper. All the horizontal lines are parallel to each other.
Perpendicular Lines	Lines that intersect at a 90° angle. Labeled as On that same lined paper, the vertical margin lines are perpendicular to the horizontal lines you write on.

Name each given shape. a) b) c) d)
a) This is a line because it continues forever in both directions.
b) This is a plane because it's defined by three non-linear points.
c) This shape is a ray because it begins at a point and continues on forever in only one direction.
d) This shape is a line segment because it begins and ends at a point. It doesn't get to go on forever in any direction.

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Name the following geometric shapes found in the image below: a line a pair of parallel lines a pair of perpendicular lines a ray a line segment the plane in which the lines lay
There are three lines: .
There are two parallel lines: .
There are two sets of perpendicular lines: and .
There are many rays in the image, including: , , .
There are many line segments in the image, including: , , .
There are many ways to name the plane. It can be named using any three points on the plane that are not in a line. Here's an example: Plane EBF.

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How many points are needed to define a line and how many points are needed to define a plane?
At least two points are needed to define a line, but there can be more than just those two points on the line.
It takes three points to define a plane, but the three points can't line up. Three non-linear points are needed to define a plane.

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How many dimensions do the following basic shapes have? a point a line a plane
A point is "dimensionless." When two lines cross over each other, they intersect at a point.
A line has one dimension (length) and, oddly enough, is created when two planes intersect.
A plane has two dimensions (length and width).

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What is the intersection of two unique, non-parallel lines?

Hint

imagine two straws meeting

What is the intersection of two unique, non-parallel planes?

Hint

imagine two pieces of paper meeting

How many dimensions does a plane have?

Hint

there is width and length