Advertisement Upgrade to remove ads


The common endpoint of an angle


two lines that intersect to form right angles


lines that never intersect


part of a line with one endpoint


extends forever in both directions

line segment

part of a line with two endpoints

acute angle

an angle that measures less than 90 degrees

obtuse angle

An angle that measures more than 90 degrees but less than 180 degrees

intersecting line

when 2 lines cross each other

right angle

an angle that measures exactly 90 degrees

straight angle

an angle that measures 180 degrees


the distance around a figure.

vertical line

A line that goes up and down

horizontal line

a line that going from SIDE TO SIDE


the space inside a shape


balance, same on both sides

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

Having trouble? Click here for help.

We can’t access your microphone!

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


Reload the page to try again!


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.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording