hey it's Kaeleigh in this lesson we will go over the basic definitions and concepts
used in geometry there are a lot of new words and descriptions so grab your
notebook to take notes during this lesson geometry is a subject of math
that looks at size shape and position of figures in their location in space this
lesson will cover the fundamentals of geometry in the geometric figures that
we are going to cover today we will talk about three things what a figure looks
like what the definition of a figure is and how we name it in geometry the first
figure we're going to cover is a point a point is a definite or specific spot in
space but it doesn't have a shape or a size notice in the picture that the
point has a label a we name points with what they are in their label so this
point is named point a now this is a line while this line looks like a
straight line it's really made up of an infinite number of points or a lot of
points a whole collection that go on indefinitely or forever in both
directions we know this because of the arrows on either end notice that two of
the points on the line have been named point B and Point C to name the line we
will use the letters for the points with a symbol above them and the symbol is a
line now we have a ray like a ray of sunshine that starts at the Sun and
spreads out forever a ray has one endpoint but extends in the other
direction infinitely notice that there are two points on this Ray one
the points is at the endpoint point D and point E is on the Ray to name the
Ray we use the two points and a symbol the symbol looks like a little ray above
the letters our next geometric shape is a line segment we know that this is a
line segment and not a line because it has two endpoints we see the two points
here and the endpoints have been named point F and point G we can name a line
segment by using the name of the endpoints with a symbol on top the
symbol is a small lime segment
intersecting lines are two lines that cross each other at a point the point
where they cross is called the point of intersection we would name this
intersection with the names of both lines so line a B is intersecting line
CD parallel lines are two lines that will never ever cross each other they
are equidistant apart we can name parallel lines with the names of both
lines and the symbol for parallel between them
the last geometric figure we will talk about in this lesson is the angle the
angle is one of the key figures used in geometry an angle is when two rays are
connected at the same point the two rays are connected at a common endpoint this
end point is called the vertex a vertex is also a type of point of intersection
we name an angle by putting all of the letters together making sure the vertex
is the middle letter so this would be angle XYZ we can write it by putting the
angle symbol in front great job learning all of the basic geometric figures study
what you've learned by doing the online games and quizzes how
fun and remember to always be clever