Compose Shapes - Geometry, Mathematics, Class 8 Video Lecture

Use these semicircles, a semicircle
semi means half
So use these half circles to make a circle
so if you take two halfs of a circle
and if you put them together just right
You're going to make a circle
So how do we do that?
Well this first choice right over here,
these are no longer the semicircles
These are each a third of a circle
So we're not gonna,
and this isn't even complete the entire circle
so that didn't make a circle
This one, they took the two semicircles
but they didn't make them
so that their outsides
completely line up with each other.
so this isn't a circle
But this one they took the two semicircles
and they put them together just right
so now their outsides line up
and we have a full circle
So that's our choice
and we got it right
Let's keep doing this
Use these small triangles
to make a big triangle
All right, well here, they used them
to make not a triangle
but this looks like a parallelogram, a quadrilateral
Here, they've used the two triangles
and made a triangle
because this whole thing has three sides
one, two, three
Here they used those two triangles
to make a square
but we wanna make a big triangle
so this is our choice
Let's do a few more of these
Use these semicircles to make a circle
Well here, they're not meeting on the flat side
so this isn't a circle
This looks like something else
like two smiles or something
Two pieces of a blue watermelon
which is sliced on top of a purple one
This is a circle
So that, they put the two semicircles
in the right way
Here they didn't even make the meet
so this would be our choice
Use these small rectangles
to make a big rectangle
Well here they didn't line them up right
to make a big rectangle
Here they did
This whole thing has one, two, three, four sides
so I'll click that one
This one doesn't look like a rectangle
It looks like some type of an L or something
So I'm not going to select that one
We got it right