## Wednesday, 8 February 2017

### Radian Measure

In some calculations in circle geometry, radians are preferred to degrees.

An angle of 1 radian is the angle subtended by an arc with the same length as the radius shown below.

### Arc Length

The formula to find the arc length is illustrated below:

Here, r is the radius and θ is the angle in radians.

If you had to find the arc length of a sector with a radius of 5cm and an angle of 80°, you would answer the question using this method - shown below.

### Area of a Sector

The area of a sector can be found using this formula.

If we had to find the area of the sector in the previous example, we would use a method like this.

#### 2 comments:

1. I remember in high school thinking that I'll never get to use these formulas ever again. Boy was I wrong. I use the circle formula way too often when I'm helping program games with my friends. Good thing that my high school teacher was persistent with me until I learned it.

my blog: http://sulfen.com

1. It is nice to know that maths still serves you to this day.