As you can easily see it is quite similar to that of a circle but modified to account for the fact that a sector is just a part of a circle. From the proportion we can easily find the final sector area formula. Insert the value for the radius and perform the remaining calculations as follows.
L th 2 p r 360 l th 360 2 p r.
Now that you know the formulas and what they are used for lets work through some example problems. A r L 2 A r L 2 Here is a three-tier birthday cake 6 6 inches tall with a diameter of 10 10 inches. To recall a sector is a portion of a circle which is enclosed between its two radii and the arc adjoining them. The area of a circle pi r2.