00:01
Okay, what we're going to do is walk through the process to be able to find the perimeter and the area of a particular shape.
00:12
And the shape we have, and of course not drawn to scale, but we'll try to do the best we can, is this shape right here.
00:26
And then we have a little angle right there.
00:29
This angle right here is 20 degrees.
00:31
This side, these are right angles.
00:37
This side is 18 meters.
00:41
This side is 16 meters, of course, not drawing properly to scale.
00:46
And then this side from here down to the bottom is 24 meters.
00:53
Okay, so remember the parameter is how far, if i have a pick a starting point, how far we would walk around completely about the shape.
01:05
And so what i need to do is one, find this length right here.
01:11
So if i go ahead and connect, we know that this will be a right angle, and this right here from here to here will be 18 meters.
01:28
So then that means this little portion of that side of that triangle is actually 24 minus 18, which is 6 .0 meters.
01:44
Okay.
01:45
And so now i can use trigonometry to find this length.
01:52
So if i think about it, that this is the angle, this is the adjacent side to that angle.
02:01
I want to find the hypotenuse.
02:03
So we know that cosine of that angle is equal to the adjacent side divided by that hypotenuse.
02:15
And so now if i cross multiply, my hypotenuse is cosine of 20 degrees divided by 6.
02:25
So make sure if you're using a calculator to do this, make sure you're into degree.
02:31
Re mode.
02:33
And then we're just going to do cosine of 20 and we're going to divide by six.
02:43
And i don't think that was and i mess that up because this really should be if i multiply both sides by h and i should have done it all, those h's and then i really should have six divided by cosine of 20 degrees.
03:05
So it really helps if you go ahead and show your work.
03:15
So this would be 6 .4 meters.
03:23
So this length is 6 .4 meters.
03:27
Okay.
03:28
And then we also need to find this length as well because when i'm walking around, i only walk this length right here, which is not 16.
03:39
So the same thing...