# Sign up for an account

Already have a Quizlet account?

Log in.

###
line

a series of points that extend in opposite directions without end.

###
ray

a part of a line with one endpoint and all points of the line on one side of the endpoint.

###
segment

a part of a line with two endpoints and all points in between.

###
plane

a flat surface that extends indefinitely in all directions and has no thickness.

###
intersecting lines

lie in the same plane and have exactly one point in common.

###
parallel lines

lines in the same plane that never intersect.

###
skew lines

lie in different planes and are neither parallel nor intersecting.

###
angle

is a figure formed by two rays with a common endpoint.

###
vertex

the point of intersection of two sides of an angle or figure.

###
point

a location in space that has no size

###
acute angle

an angle less than 90 degrees but more than 0 degrees

###
obtuse angle

an angle between 90 and 180 degrees

###
right angle

an angle that measures 90 degrees

###
straight angle

an angle of 180 degrees

###
complementary angles

Two angles whose sum is 90 degrees

###
supplementary angles

Two angles whose sum is 180 degrees

###
adjacent angles

are a pair of angles with a common vertex and a common side, but no common interior points

###
vertical angles

opposite angles formed by two intersecting lines

###
congruent angles

angles that have equal measures

###
congruent sides

sides that have the same length.

### Please allow access to your computer’s microphone to use Voice Recording.

## We can’t access your microphone!

### Click the icon above to update your browser permissions and try again

Example:

### Reload the page to try again!

Reload

## Press Cmd-0 to reset your zoom

## Press Ctrl-0 to reset your zoom

### It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

## Your microphone is muted

### For help fixing this issue, see this FAQ.