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0:02 [Music] Okay, peace be upon you, meet again with our channel, great mathematics, in our video this time we will try to discuss the material, namely the length of the arc and the area of the circle sector, but before we continue, don't forget to like, subscribe, comment and share our video, hopefully the video is useful and hopefully it can be a charity for us later and now let 's just discuss the example questions, but before that, first here we will try to briefly explain the formulas used in
0:47 determining the length of the arc and the area of the circle sector as follows. Now, practice the first part of the formula. This first part of the formula can be used if in the question there are two large angles or it may also be known that in the question there are two arc lengths or it may also be known that in the question there are two areas of the circle sector, then that's the provision for using this first formula, but if for the second part of the formula it can be used if in the question there is only one large angle and there is a radius of the circle, then we use this second part of the formula.
1:33 Well, to be clearer about the use of this formula, let's just discuss the example questions, pay attention to the first question, a picture is given then Determine a the area of the sector aob then which B is the length of the AB muscle now pay attention to the steps or how to solve it for part a first, namely the area of the sector aob l the sector aob is equal to Okay, pay attention to the picture again in the picture here which is known that there is only one large angle and there is a radius of the circle, then the formula that we use is of course the formula for the second part. Well, where is the formula for the
2:18 second part to determine the area of the sector of the circle, namely Alpha degrees per 360 degrees multiplied by the area of the circle, this is the formula for determining the area of the circle sector, the same as for Alpha degrees, namely the size of the angle in the problem, the size is 90 degrees per below 360 degrees multiplied by the area of the circle What is the formula for the area of the circle, namely V * r^ is the same as the number 90/360, this number can still be reduced or simplified, namely
3:04 both are divisible by 90 for the top number 90 if divided by 90 the result is 1 while the bottom number 360 / 90 the result is 4 then the simple form of 90/360 is 1/4 then multiplied by V remember there are two types of V, there is 22/7, it is used If the value of r or the radius multiple of 7 while the other V which is 3.14 is used If the value of r or the radius is not a multiple of 7 now we check first for the radius value which is 14 well 14 is a multiple of 7 then the V used is
3:52 22/7 then multiplied by R the radius is 14 don't forget to square it because the formula is squared then equal to 1 * 22 the result is still 22 per below 4 * 7 the result is 28 then multiplied by 14 k we get the result which is 196 the same 22 * 196 the result is 4,000 312 per below 22 eh sor 28 we mean the same as 4,312 / 28 we get the result which is 154 in the unit here centm So
4:40 if the unit for the area is centm² and like that the way to determine the area of a sector of a circle continue to question part B which is about the length of the arc AB the length of the arc ab is equal to remember the formula we use is formula for the second part Why Because what is known in the question is that there is only one large angle and there is a radius of the circle, so the formula that we used was the second part formula okay now where is the second part formula to determine the length of the arc AB, namely pay attention here Alpha
5:28 degrees per 360 degrees multiplied by the circumference of this circle, the formula continues to be the same as alpha, namely the size of the angle in the question is 90 degrees per below it 360 degrees multiplied by the circumference of the circle What is the formula for the circumference of a circle, namely 2 * v * r the same remember 9 / 360 this number can still be reduced or Simplified, namely both are divisible by 90 we get the simple form earlier, namely 1/4 then multiplied by 2 times V which is
6:14 used the same as the question part A earlier, namely 22/7 multiplied by R the radius is 14 is the same as Now pay attention to the multiplication method, we just multiply the top part first 1 * 2 * 22 then multiply again by 14 here we get the result, namely 616 per below it, namely 4 * 7 the result is 28 and 616 divided by 28 we get the result, namely 22 in centimeter units and like this the solution is easy, not very easy of course, well, let's continue to really understand the example of the second part of the question,
7:02 an image is given, then in the question it is known that there is a COD sector area, this COD sector is the sector that is 48 cm per, then there are two lengths of the first circular arc, arc AB which is 30 cm long and arc c which is 12 cm long, remember if in the question there are two lengths of circular arcs, then the formula used earlier is of course the first part. Well, pay attention here to how to use the first formula that is asked for the area of the AOB sector, then here we first write l
7:52 AOB sector per, pay attention to the area of the other known sector, namely the COD sector, l COD sector is equal to Pay attention to the top, namely the AOB sector, then the first we take again is the arc from AB, pay attention to AB, the arc length is 30, here we write the AB arc per, below it is the COD sector, then the arc we take is the CD arc, arc CD Now, we just enter the number l
8:37 AOB sector, which we will find per below it, the COD sector area is already known where the size is 48, equal to the ABI arc It is already known that the size of 30 per below the arc CD is already known that the length is 12 then for the area of the sector aob is the same as we just multiply it crosswise first 48 multiplied by 30 48 * 30 per below the number below here, namely the number 12 is equal to 48 * 30 we get the
9:23 result which is 1440 per dib 12 and 1440 / 12 we get the result 120 in the unit here the unit is centm So if the unit for the area we just add the power of 2 or read centm² and so on the way to determine the area of the sector of a circle if using the first part of the formula is easy, not very easy of course Okay, that's our sikkat tutorial, hopefully it's useful More and less we apologize, we close with Assalamualaikum warahmatullahi wabarakatuh
