The Parthenon of the Acropolis, Athens, Greece
The Greeks invented plane geometry more than 2,000 years ago. Plane geometry studies shapes in two-dimensions, like on a flat sheet of paper. You can imagine shapes in your mind or draw them on a piece of paper. Geometry is all around us, from architecture to engineering, even in nature!
There is some important words you need to know to work with geometry. Once you know these facts, geometry is a lot of fun!
point
line
line segment
parallel
intersecting
perpendicular
angle
ray
vertex
acute
right
obtuse
straight
triangle
quadrilateral
square
rectangle
parallelogram
trapezoid
rhombus
pentagon
hexagon
heptagon
octagon
nanogon
decagon
undecagon
dodecagon
Intersecting lines
Perpendicular lines
Parallel lines
Acute angle
Right angle
Obtuse angle
Lines and angles
Mr. Mamontoff 