Lesson 5­2 Arc Length & Area of Sectors In your groups, find the area of the shaded regions. 210o 5 cm 5 cm 5 cm Lesson 5­2 Arc Length & Area of Sectors Objectives Find circular arc length and areas of sectors. Solve problems involving lengths of arcs or areas of sectors. Lesson 5­2 Arc Length & Area of Sectors Lesson 5­2: Arc Length & Area of Sectors Before we can calculate the length of arcs on a circle and the area of a sector of a circle, we need to recall a couple of formulas. Under each of the headings, write out the formula that is asked for. Circumference of a Circle Area of a Circle C = 2πr A = πr2 disk ­ the union of a circle and its interior sector of a circle ­ part of a disk that is on or in the interior of a central angle. Lesson 5­2 Arc Length & Area of Sectors Circular Sector Area Formula If A is the area of a sector formed by a central angle of Ѳ (radians or degrees) in a circle of radius r, then Lesson 5­2 Arc Length & Area of Sectors Circular Arc Length Formula If s is the length of the arc of a central angle of Ѳ (radians or degrees) in a circle of radius r, then Lesson 5­2 Arc Length & Area of Sectors Example 1 Find the length of an arc of a 135o central angle in a circle of radius 12ft. 135o 12ft Lesson 5­2 Arc Length & Area of Sectors Example 2 A sector has a central angle measure of π/3 and a radius of 5cm. Draw a picture to represent the situation. Then find the arc length and area of the sector. Lesson 5­2 Arc Length & Area of Sectors Example 3 A sprinkler with a radius of 20 meters can water 400 π/9 m2 of land in 30 minutes. Find the central angle and the time needed for the sprinkler to complete a full revolution. Lesson 5­2 Arc Length & Area of Sectors Group Practice Problems Answers Lesson 5­2 Arc Length & Area of Sectors Homework Lesson 5­2 p.276 #1­19 skip 9­11,13.