Area of circle - Circumference of circle - Volume of cylinders - By tecmath
Transcript
| 00:01 | this video looks at the area , the perimeter and | |
| 00:05 | the volume of some circular shape . Some of the | |
| 00:08 | basic terms we're going to be using them as following | |
| 00:12 | . The first time we're looking at is the radius | |
| 00:14 | . The radius is the distance from the center of | |
| 00:17 | the circle to the outside of the city . Okay | |
| 00:21 | . It doesn't matter where you talk about On the | |
| 00:24 | outside . The circle , distance from the middle to | |
| 00:28 | the outside is always the same . The next time | |
| 00:30 | I'm gonna be looking at as a diameter diameter describes | |
| 00:33 | the distance across the span of the circle . What | |
| 00:35 | you probably realize is this is twice the distance of | |
| 00:38 | the radio . The next one will be using as | |
| 00:41 | a sort of conference . The circumference is the same | |
| 00:43 | as saying that the perimeter of a circle and it's | |
| 00:46 | a distance around the outside of the circle . Final | |
| 00:49 | thing we're going to be using this greek letter pi | |
| 00:52 | Pika was 3.14 . And it's simple just showing . | |
| 00:57 | And this constant Number 3.14 , you'll be using a | |
| 01:02 | fair bit when you're working with circles . So first | |
| 01:06 | off , we'll have a look at the area . | |
| 01:10 | Okay , so the area of a circle this pie | |
| 01:13 | are square , which means pi times are So we'll | |
| 01:16 | consider where we have a radius of five cm substituting | |
| 01:20 | the value in area equals pi times five squared , | |
| 01:24 | Which equals 3.14155 , which multiply those out , gives | |
| 01:29 | us an answer of roughly 78 cm switch . Okay | |
| 01:34 | , that's a look . Another example In this example | |
| 01:37 | we have a radius of 11 m . So we'll | |
| 01:40 | substituting the values . So the area equals pi times | |
| 01:45 | 11 tom's 11 . This equals 3.14 Times 11 times | |
| 01:52 | 11 , Which equals 380.13 m squared . Okay , | |
| 01:58 | so we're working in the area , just a simple | |
| 02:00 | matter substituting the radius into that formula pi R . | |
| 02:04 | Square . Next we'll have a look at the circumference | |
| 02:08 | . So as you remember the circumference is the same | |
| 02:11 | as saying the perimeter of the circle . It's a | |
| 02:13 | distance around the outside . The circumference equals two pi | |
| 02:16 | R Once again the system matter of substituting in the | |
| 02:19 | value . So so the radius is nine cm . | |
| 02:22 | The circumference equal to transpire comes north , which he | |
| 02:27 | was through From 3.14 times nine . Which when you | |
| 02:32 | calculate it is 56.55 cm . With another example . | |
| 02:40 | So in the next example We have a diameter which | |
| 02:43 | is nine cm . Okay so we have to work | |
| 02:47 | out the radius is The radius is gonna be half | |
| 02:49 | a diamond , so half of nine is 4.5 cm | |
| 02:53 | . And we just substitute this into the formula circumference | |
| 02:55 | is two pi was 4.5 Which is two times 3.1 | |
| 03:02 | , x 4.5 . Which gives us an answer of | |
| 03:04 | 28.28 cm . And that's a circumference . Next time | |
| 03:10 | we'll look at working out the volume of a cylinder | |
| 03:14 | . Well considering the volume of a cylinder , where | |
| 03:17 | I'll give you a big fancy formula . First off | |
| 03:19 | , let's get you consider the different parts . Now | |
| 03:21 | , the area of the circle part of a cylinder | |
| 03:24 | , but we've already seen as pi R squared . | |
| 03:26 | The other thing we deal with is the heart . | |
| 03:29 | So how do we use this to to work at | |
| 03:30 | the volume of the some of the world ? The | |
| 03:32 | volume who call it simply is the area of the | |
| 03:35 | circle times the height . So we could work that | |
| 03:38 | out and formula very easily . So the area is | |
| 03:42 | pi R squared , so the volumes by us where | |
| 03:45 | times the height . So let's use this to work | |
| 03:48 | at the volume of a few different cylinders . First | |
| 03:51 | off , let's work on where we've got A radius | |
| 03:55 | and the cylinder of four cm and a high of | |
| 03:58 | 11 cm . So what we'll do is of shading | |
| 04:03 | the circle part and leave the other high part of | |
| 04:06 | blank so you can separate the two first started . | |
| 04:09 | So pi r squared is 3.14 x four x 4 | |
| 04:12 | Heart . Still Times 11 . So it was 50.2 | |
| 04:16 | , 7 times 11 . So at times at least | |
| 04:18 | together and you get 552.92 cm sq Hollywood with another | |
| 04:24 | example here and once again , I'll show it again | |
| 04:27 | . Here . We have a diameter of 12 m | |
| 04:30 | and a height of 17 m . So the writing | |
| 04:32 | is going to be half of The diamond , which | |
| 04:34 | is six m . or substitutes . Why are squared | |
| 04:38 | is 3.14 x six x 6 time 78 Working this | |
| 04:44 | out , this equals 13 , 10 time 17 . | |
| 04:47 | So the volume of the cylinder was 1922.65 m acute | |
| 04:52 | . So anybody sum it all up . First off | |
| 04:55 | , the area of a circle is pi R squared | |
| 04:59 | . Well , Pi is 3.14 R . is the | |
| 05:01 | radius circumference was several . The perimeter is to empire | |
| 05:07 | the volume of the cylinder . It's basically the area | |
| 05:10 | pi R squared times the height . So if you | |
| 05:14 | can work that out , you should do well with | |
| 05:15 | circular shapes . Good luck with that . |
Summarizer
DESCRIPTION:
OVERVIEW:
Area of circle - Circumference of circle - Volume of cylinders is a free educational video by tecmath.
This page not only allows students and teachers view Area of circle - Circumference of circle - Volume of cylinders videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.
GRADES:
STANDARDS:
