00:01
If you're trying to find the area of a composite figure like the one you see here, then remember the composite figure is the total area inside of this shape.
00:09
So basically they're talking about this entire space and i'm highlighting in yellow.
00:14
And you find the area of all that.
00:17
Okay.
00:18
Now whenever you're working with a composite figure like this, it's called a composite figure because there are two figures that you can separate it into or more, that you can find the area of those individual figures and then have them together.
00:30
This top part here is a semicircle.
00:34
So you want to make sure that you're thinking about that as a semicircle.
00:38
And then this bottom area is a rectangle.
00:43
So a rectangle and a semicircle.
00:45
And we're going to add those together.
00:47
Now, the area of the semicircle, ok, let's do a little half -minute circle there for you so you can see the area of the semicircle.
00:55
It's going to be equal to half of a circle.
00:58
So it's one half, the area of a circle.
01:00
The area circle is pi r squared.
01:03
Okay? so we're going to figure out the radius of the semicircle.
01:07
And it says that the diameter is five as the distance across from edge to edge through the center.
01:12
So that means that the radius is going to be half of five, which is 2 .5.
01:19
So we can just take the diameter and cut in half to get the radius.
01:23
So that means that we're going to have an area that it's one half of pi times 2 .5 square.
01:32
And when we want to do that, 25 squared is 625.
01:37
So 2 .5 square is going to be 6 .25.
01:41
So what we really have here is 0 .5 times pi times 6 .25.
01:51
And remember, half is just .5s is half.
01:55
Cut that in half, half of six is three, half of point two five is point one to five.
01:58
So really what we have here is 3 .125.
02:02
Times pi and it would be in kilometers square.
02:07
That's exact, but it's not very helpful to us because we don't have the approximated actual area in square units that we want is in pi notation.
02:16
So you're going to approximate that by multiplying that 3 .125 by the approximate value of pi, which is 3 .14...