Advertisement Upgrade to remove ads

Geometry lessons 1-7

intersection

point where two or more lines cross

equilateral

triangle with 3 equal sides

corresponding

angles in the same position at different points of a figure

protractor

tool used to draw or measure angles

ray

set of points that is part of a line; has an endpoint and extends

vertex

common point to both sides of an angle

acute

angle smaller than 90 degrees

vertical

pairs of opposite angles; have the same measure

right triangle

triangle with a 90 degree angle

supplementary

two angles whose sum of their measures is 180 degrees

straight

angle measuring 180 degrees

isosceles

two of the sides in a triangle are the same

equiangular

triangle with 3 equal angles, measuring 60 degrees

interior

angle within a polygon

acute triangle

a triangle with all 3 angles less than 90 degrees

obtuse triangle

triangle with one obtuse angle

obtuse

larger than 90 degrees

adjacent

angle that shares a vertex and a common side with another angle

right

a 90 degree angle

complementary

two angles whose sum of their measures is 90 degrees

exterior

angle formed by extending one side of a polygon at a vertex

scalene

all the sides of a triangle have different lengths

congruent

having the same size and shape

similar

figures that have the same shape but not the same size

quadrilaterals

polygons with 4 sides and 4 angles

diagonal

a line that connects two vertices that are not next to each other

regular polygon

polygon with all equal sides and angles

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

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.

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

Create Set