Angle basics and measurement
Angle basics Definition of an angle. How to denote an angle using points on the angle (including the vertex)
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- Lets say we have one ray over here that starts at point A and then goes through point B, and so we could
- call this ray (we could call, let me draw that a little bit straighter) we could call this ray AB. Ray AB
- starts at A or has a vertex at A and lets say that there is also a ray AC. So lets say that C is sitting
- right over there and then i can draw another ray that goes through C, so this is ray AC. and what's interesting
- about these two rays is that they have the exact same vertex. (they have the exact same vertex at A)
- and in general what we have when we have two rays with the exact same vertex, you have an angle. and
- you've probably, you're probably already reasonably familiar with the concept of an angle which i believe
- comes from the latin for corner, which makes sense this looks a little bit like a corner right over
- here that we see at point A and, but the geometric definition, or the one you are more likely to see
- is when two rays share a common vertex. and that common vertex is actually called the vertex of the angle.
- so A is vertex. Not only is it the vertex of each of these rays, ray AB and ray AC, it is also the vertex
- of, of the angle. so the next thing i want to think about is how do we label, how do we label an angle
- you might be tempted to just label it angle A, but i'll show you in a second why that's not going to
- be so clear to someone based on where, where our angle is actually sitting. so the way that you specify
- an angle, and hopefully this will make sense in a second, is that you say ANGLE, (this is the symbol
- for angle) and it actually looks strangely similar to this angle right over here, but this little pointy
- thing almost looks like a less than sign, but it's not quite. its flat on the bottom right over here.
- this is the symbol for angle, you would say angle BAC, BAC, or you could say angle CAB, or angle CAB.
- and either case there kind of specifying this corner, or sometimes you could view it as this opening
- right over here. and the important thing to realize is that you have the vertex in the middle of the
- letters. and you might be saying why go through the trouble of listing all three of these letters, why
- can't i just call this angle A. and to see that, let me show you another diagram. and although the geometric
- definition involves, two rays that have the same vertex
- in practice, you are going to see many angles
- made of line and line segments
- Lets say I have one line segment like that, let me
- label it DE, and lets also have line segment, FG
- and lets say the point where the two line segments interact
- is H, how could we specify this angle right over here
- can we call it as angle H, if we say it as angle H,
- it could be this angle, that angle or this angle over here
- it could be this angle over here. The only way to specify
- which can we are talking about is to give 3 letters
- if you want to talk about this angle, you will call it
- angle EHG, or could call it angle GHE,
- if you wanted this angle over here, you could call it
- angle DHG, or angle GHD. i think you get the point.
- this angle is angle FHE or EHF and this is angle FHD or
- DHF. now are are clear which angle you are referring to.
- So now we have a general idea what an angle is and how
- we denote it with symbols, it does not look like
- all angles look the same. Some are more open than others
- So for example, let us take two angles here,
- angle BAC, and let's say over here, I have angle XYZ
- when you look at these angle XYZ is more open
- while this angle is more closed, compared to the other angle
- when we measure angles, we must measure it on how open
- or closed they are. The measure of angle XYZ, is greater
- than the measure of the angle ABC.
- Any measure of angles, is based on how open, or closed
How are Angles used in everyday life?
Many ways. Architecture cannot be created without using angles and their measures. Another place is in design. In clothing, there are different angles in different sizes. One place people don't think about is in music. If you don't write the notes and accidentals with the right angle measures, you could end up with something totally different than what you wanted. The final area I would like to mention is in animation. During creation, the animation workers must create the picture with angles… (more)
Natalie S Corvino
Cameron14
yoanante
lockett.dajuel
AZUGERE
jacob
69812
how many angles can you think of?
Lloyd aka Green Ninja
Besides the 4 types of angles tabron517 mentioned, there are also full and reflex angles. A full angle is a full 360 degrees and a reflex angle is between 180 degrees and 360 degrees. A full angle looks like this: https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Full_angle.svg/380px-Full_angle.svg.png An obtuse angle is between 90 and 180 degrees and a straight angle is 180 degrees.
Hopefully you know the rest: acute --> less than 90, right ---> 90. In between, there's an… (more)
Hopefully you know the rest: acute --> less than 90, right ---> 90. In between, there's an… (more)
Boris Stanchev
BRELAND H.
Shubhodiya
In the first diagram, is there any way to refer to the reflex angle (one thats > 180 degrees but < 360 degrees) on the "outside" of the two rays? By this I mean if you look at the rays as a sliver of a circle, you actually have two angles - an acute "interior" angle and a reflex "exterior" angle- which together add up to a full 360 degrees. In this case couldn't you refer to both angles as angle BAC? I'm sorry if I've confused anyone, it just struck me that this naming convention could… (more)
Actually, there are two angles that add up to 360. BUT! you would need to distinguish the two from each other with "<" and ">" (Acute & Reflex, respectively).
Is a vertex the meeting point between two rays or two line segments or two lines, or does it not matter?
Well, if you look at a angle, it has no arrows, but is still is a ray, and still goes on forever, the angle just doesn't have the arrows. I believe that angle are all rays, but I am not sure. It would be good question to google. Hope this was helpful to you!
contractor.taha
would DHE be an angle
yes, because there are three points, or letters
Stephanie Hansen Cullen
who invented angles? my teacher wants to know
A couple of different persons, just who made it public?
rishika.pt118
How does a Line differ from a Ray
Line: A geometrical object that is straight, infinitely long and infinitely thin.
Ray: A line which starts at a point with given coordinates, and goes off in a particular direction to infinity, possibly through a second point.
Ray: A line which starts at a point with given coordinates, and goes off in a particular direction to infinity, possibly through a second point.
This helped a lot, thank you.
yes you are good
so if an angle is ABC should I put BCA or CBA
you should put BCA because it is backwards.
What is a vertex?
And where is the starter video?!
And where is the starter video?!
A Vertex Is Where 2 Points Meet
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