### Video instructions and help with filling out and completing How Form 1094 B Index

### Instructions and Help about How Form 1094 B Index

Vidiyal is going to talk about how to find the arc length assert their heart first thing we have to realize we're giving some radius by some angle we're trying to find the sr5 that is officer all right that is part of a circle so instead of development of formula but you can't remember going to talk about problems we can understand and then figure out how to do it in the future so if I say find the arc length s2 following case for fading equals Tyree we know that Iranian for those needs openal radiant eyes above 90 degrees so we know that this case has gradient though hi but we can also write this as a first of 180 degrees well we know how the answer this pretty quickly just using our logic we know the distance all the way around the circle it's called comfort you know that's equal to 2 pi r or pi d we know we had a radius three so at this time we would agree the diameter six inches so it's a comfort to the entire circle a 6 pi interest well it's obvious that we only have half of the surface so it's pretty easy to take tap all 65 in this case s is going to be the arc length here will be 35 the real question is how do we tied that is something that makes sense when it's not so obvious what you have to pick up here is you knew it was half because the how many degrees out of how many well circle always has 360 it's always proportional in this case you have to catch the degrees are proportional to the arc length and this compass anytime you're asked to do this you can quickly set up a ratio so if I have another problem we have a circle will often they show the circle let's make the radius of this circle five inches and let's find the arc length of your 10 degrees okay we know it's over half all right you know it's over half now in terms of radiant if we were thinking about what this is we can figure that out too but we'll skip that in this case we know when we have to learn 10 degrees out of 360 degrees we know that this here is the arc length which I have called s off on strike through it that's a quick let matches the tour 10 degrees what arc length matches 36 the whole way around is the circumference so again 2 PI R or PI D is the circumference well use 2 PI R since it's given us a radius to 5 times 5 inches all right and once we have the ratio the two ratios set in the proportion we can cross multiply and divide I'll get I'll simplify 2136 s over and by inches purple actually those are both divisible by 3 I get 7 12 people pass over 10 pi and chisels cross multiply in 12 s equals 7 times 10 I inches divide both sides by 12 finally I like to leave this in terms of Phi I see that fall in 10 both have a common so I'll say the arc length in this case is 35 65 inches I just followed the arc length of this circle now you're looking for a general equation you can develop it by using this situation here we are looking for an angle out of the possible of the glue 360 degrees so your ratio is always beta over 360 park / tour in this case the park is is the total in blue maybe I should you faded here in red total this time again all the way around is comfortable to high office will set up on that so that is equivalent that goes with 360 all right how do you solve for s once it across multiplying CS very anti if i multiply both sides by 2 pi r so i get an equation theta over 360 degrees times two PI R 4 equals the arc length s that does work every time if you look at it it is a ratio when what's happened was one eat it was half of 180 or 360 you can kind of picture that timeless compass it is always a racial mr. functions and this is how we find our cuento now I'm gonna put a couple examples of all right if you pause a bit you can work these out yourself again I'm going to do as a ratio and again if you're not used to radians first thing we do is put on 80 degrees in 53 180 divided by two is 99 hemstreet we have 270 degrees I want the matching arc length here going to call it arc length again ass and again i'm going to set up racial it's always a part of the angle of the total to 70 or 360 or that ratio the ratio of the arcs which is hard park which is the arc length s over the total arc which is this conference again the radius is 4 diameter is 8 so i'll write this to me pi centimeters and again i can simply multiply x 85 centimeters only 270 over 360 reduces three fours or x 85 centimeters I'm going to find the arc length from the top problem for 657 the next one red I'll grab my pen again find the arc length here for an angle of 60 degrees for the radius that show us two down it was part 60 degrees of the part out of 30 6 degrees so it opal equal to alcohol eh? that was called over 2 pi r all right well this time airs for so I more or five inches again i'll multiply both sides by 4 x 60 over 360.