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Hello, my name is Maria Miller from MathMyMoth.com. In this video we are going to study how to

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draw a right angle and a rectangle. And this drawing a right angle is good for about third

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grade math. Drawing a rectangle is both for third and fourth grade. And you need a tool

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to do this and I am going to use a protractor first of all. Let's say here is your line

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and you need to draw a right angle. It means you need to draw another line here that goes

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at a right angle with your existing line. Okay? So you have to position your protractor

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so that this is going to be where you're going to draw. You're going to draw along this line,

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right? This side. And so just position your protractor so that your 90 degree mark here

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lines up with your existing line and then the midpoint here, however it is marked, has

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to line up with your line too. And then you just draw. So it's pretty simple. I'm going

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to show you also how to do this same thing using a triangular ruler. This is a triangular

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ruler and we can also use this to draw a right angle or actually to draw a line that goes

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at the right angle called a perpendicular line. Again you need to use this side to actually

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draw your line. So just position your ruler so that this corner here is exactly at your

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existing line, and then you have to find your midpoint here, which in my ruler it is the

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number 8 is marking the midpoint, so that has to line up too. Go exactly at the existing

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line. There, and now I'm ready to draw the line. Okay, that makes a perpendicular line

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and my right angle is of course here now. If need be, I could then erase this line or

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whatever is needed to be erased. I'm going to change back to my protractor because that's

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what I prefer. A common exercise that's given is to draw a perpendicular line or a right

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angle so that it is at this given point, so that the line goes through this point. So

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again, you're going to draw along this side. So just put this one here. Oh, I need to do

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it this way this time and then line up the 90 degree mark over here with the

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existing line there a little difficult okay like that here's my right angle oh

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it could be that you have to draw your line so that it goes through a point

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that is not on the existing line again you just have to line up you're gonna

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draw over here and then you have to line up your 90 degree mark and the dot

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and everything. It takes some practice to line up everything. Then you're ready to

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draw. So here I could get my 90 degrees. Now you can also use this method to draw

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a parallel line. Let's see how that goes about. I would first draw a line that is

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perpendicular, a line that is at the right angle, then another line that is at

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the right angle with my first line. Okay, first I will draw just any line that is

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at the right angle, using the same method here. Now I will draw a line that is at the

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right angle with this red line. Okay, I can't see my 90 degree mark, I better continue this

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line some more here. Now I can line up my 90 degree mark here and then just draw a line

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here. So I got the line that is parallel to the existing line. Of course there are other

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methods for doing this too. But this is if you are allowed to use a protractor or a triangular

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ruler. Lastly, we're going to draw a rectangle. And I wrote here 50 centimetres and 20 centimetres

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because that's how big I have to draw it so that it won't be just a teeny one here on

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the board. But for students who are drawing it on the paper, they need to use smaller

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numbers because 50 centimetres would exceed paper size, so maybe 10 and 4 centimetres

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or something like that. Now we will start out by drawing first the one side of the

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rectangle and I need this for drawing the right angles and then a normal ruler

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for drawing longer lines. So let's draw first a line then I need to measure on

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it the 50 centimeters here and here and now let's draw a line that goes at the

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right angle. The best we can, as accurately as we can. There. And on this side, there's

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a lot of lining up to do and it is hard to be 100% accurate. So, don't be surprised if

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these don't exactly match with, don't look like rectangles. Okay, I need my centimeters

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here to measure 20. There, now I have marked the 20 cm and 20 cm. So, now I should be able

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to just draw a line from here to here. And here's my rectangle.