Geometry: Introduction to Geometry (Level 2 of 7) | Draw, Denote, Name Examples

Geometry: Introduction to Geometry (Level 2 of 7) | Draw, Denote, Name Examples


Introduction to Geometry (Level 2)
Alright in this video we are going to practice
drawing, denoting and naming figures with
a couple of examples, to be successful in
geometry you need to be able to read and describe
the basic building blocks of geometry both
pictorially and symbolically. Let’s go over
the first example:
Draw a figure that represents the following symbols. Line segment PQ, line PQ, Ray PQ, angle PQR, and trianlge PQR.
Alright the first symbol represents a line
segment since there is a line segment drawn
directly above the letters. We can draw this
segment by drawing two points P and Q and
connecting them with a straight line as follows.
Remember line segments have a definite length
they have a beginning and an end. They do
not extend forever and ever in either direction.
The next symbol represents a line since there
is line with arrows pointing in opposite directions
drawn directly above the letters. This is
similar to a line segment the only difference
is that this line extends infinitely in both
directions we show this by drawing arrows
on both ends. So we first draw points P and
Q and then we connect them making sure we
draw arrows on both ends as follows.
The next symbol represents a ray. Since we
have a line that extends in one direction
drawn directly above the letters. The first
letter in the symbol always represents the
end point of the ray; keep this little detail
in mind. So we first draw points P and Q and
then draw an arrow that extends from point
P towards point Q as follows. It would be
incorrect to draw this ray the other way around
since the symbol is stating that the end point
starts at point P not point Q.
The next symbol represents an angle for the
most part we denote angles using three points,
the middle letter always represents the vertex,
so we go ahead and draw point P,Q and R, then
we draw two rays both emanating from the vertex
Q as follows. You need to make sure that the
vertex is being represented by the middle
letter in this case point Q. It is very important
to pay attention to these little details.
The final symbol represents a triangle, and
like an angle it also requires three points,
in this case each of the points will be connected
by a line segment. So we first draw points
P,Q and R, then we go ahead and connect them
in the order represented by the symbol, so
P connects with Q and Q connects with R and
lastly you form the triangle by connecting
point R and P.
Make sure you comfortable reading and drawing
the various types of lines, rays, angles and
triangles. Since you will be reading and drawing
them extensively in your geometry class. It
is important that you master this skill before
we tackle more challenging problems in geometry.
Alright now let’s practice denoting and
naming geometric figures. Let’s move along
to the next example.
What are the three possible names for the
line shown?
Recall that lines contain arrows pointing
in opposite directions and can be denoted
by using two points in this example the line
shown can be denoted by using point C and
point D so we can name the line as “line
CD or line DC” making sure we draw a line directly
above the letters. Alternatively, we can also
name this line as line l since this line is
also labeled with a lowercase letter. Keep
in mind when we use two points to denote a
line we usually want to express the points
in alphabetical order, never the less both
expressions are acceptable ways to name the
line. Alright let’s try the next example
What are four possible names for the angle
shown?
The following angle can be named in various
ways, since this diagram only contains a single
angle with point E as its vertex, we can use
the vertex to name the angle in this case
point E so we can name this angle as: angle
E making sure we draw the picture of an angle
followed by the letter of the point that represents
the vertex. Alternatively, the angle is also
labeled with the number 5 so we can also name
this angle as: angle 5. We can also name angles
by using 3 points in this case we can use
point C, E and D to name the angle, so we can
name this angle as: angle CED or angle DEC
making sure we write the point that represents
the vertex in the middle. Just like lines
we usually want to denote the points of an
angle in alphabetical order whenever possible.
Nevertheless both forms are acceptable ways
to name this angle. Alright let’s try the next example.
Name the sides of triangle RST.
Here we have a triangle, recall that triangles
contain 3 angles, hence the name triangle,
this also means that triangles are formed
by three sides. We can name the sides the
same way we name line segments by using two
points. In a triangle the points we will use
are the once located on each vertex of the
triangle. These vertices are essentially the
end points of a line segment. The first side
contains points R and S and can be named as:
line segment RS or line segment SR the second side contains
points S and T and can be named as: line segment ST
or line segment TS and the third side contains points
R and T and can be named as: line segment RT or line segment TR, Making sure we draw a line segment, to
symbolically show that we are referring to
a line segment not be confused with rays or
lines. Once again it is very important that
you master this skill of drawing, denoting
and naming figures. In our next video we will
practice how to name and denote angles.

28 thoughts on “Geometry: Introduction to Geometry (Level 2 of 7) | Draw, Denote, Name Examples

  1. The goal is to expand the library of videos to include that topic and much more! Unfortunately we can only generate one video every week at our current capacity. You can help out by spreading the word about Math Fortress.

  2. Not yet. We are planning of expanding the library on one math topic, we are analyzing to see which math topic is in demand.

  3. I cried in geometry class today, I wasn't understanding anything. So I decided to find help on here good thing I did I was begining to worry how I was going to pass. Thank you very much for helping me have a better understanding.

  4. …MATH FORTRESS 2!!! … anyway these videos are great, I'm learning a lot, I have to take a college assessment soon and i want to get a high score on the math portion of it 😀

  5. How can you determine so easily that the angle PQR is made up of rays and not segments or lines? at mark 2:19?

  6. Your videos are so much understanding. My geometry teacher teaches us nothing, but gives us notes.
    Because of you, I’ll be better at geometry. Thank you!

  7. I'm starting Geometry Honors in the 9th grade, which is in 2 months. This video was a good starting point to learn the basics.

Leave a Reply

Your email address will not be published. Required fields are marked *