 The total area of three blades of a windmill is two hundred and seventy pi meter squares. The blades form an angle of 36 degrees at the centre. Find the radius of each blade. So we have the blades of our windmill here, although I haven't quite drawn out the tar of this windmill, but you get the idea right? So let's figure out the radius of each of these blades. So the blades of a windmill, they move in a circular fashion. So we can say that each of these blades is actually a sector. It forms a sector of the circle. And if we find out the radius of the sector, we'll be able to figure out the radius of each of these blades. So let's get started. So now, what if we had a sector which made an angle of 360 degrees at the centre? Now that would mean we would have a complete circle. And we already know that the area of a complete circle is pi r squared, which in other words we could say that is the area covered when a sector subtends an angle of 360 degrees at the centre. Now, if we had a sector which made an angle of one degree at the centre, then we could say that the area of this sector, the area of this sector which makes an angle of one degrees at the centre would be pi r squared times one degree divided by 360 degrees, right? So this means if we have any sector which makes an angle of theta at the centre, we can say that the area of this sector would be pi r squared times theta divided by 360 degrees. So this gives us the area of any sector. So let me just mark it out for you and you can arrive at this result using this method. You don't need to memorise this as a formula. So as each of the blades of this windmill is a sector, we can say that the area of each blade is equal to pi r squared times the angle it subtends on the centre which is 36 degrees divided by 360 degrees. So this gives us the area of a single blade. If we multiply it by 3, we will get the total area of the three blades. We multiply it on to this side as well and this total area is given to us as 270 pi metres squares. So now let's solve this to find the value of r. If I just copied this and put it here because I don't have enough space, let's do this now. So 36 times 10 is 360. We have pi on both the sides and if we divide both the sides by 3, we will have 3, 9s are 27 and if we multiply both the sides by 10, we will get r squared r squared equals to 900. So if we take the principal square root of r here, we will have r equals to 30 metres which gives us the radius of each blade of our windmill.