Warm-up 4/29/15.1) Find the arc length of the given circle.

Warm-up 4/30/15.1) Find the circumference of the given circle.

2) Find the area of the given circel

Announcements 4/30/15.1) I will give 3 pts extra credit to the first 10 people

that bring large tissue boxes.2) Homework 7.4 will be due Thursday.3) Test on Tuesday May 5th and Wednesday May 6th

7.4 Sectors and Segments

Recall:C = 2 rA = r2

Q: What are the dimensions for length?A: 1, so the exponent on the units should be one, i.e. cmQ: What are the dimensions for area?A: 2, so the exponent on the units should be two, i.e. cm2

Definitions.A Sector of a Circle is the region bounded by two radii and the intercepted arc.A Segment of a Circle is the region bounded by a chord and its intercepted arc.

Theorems 7.8 If the degree measure of an arc is and the circumference of the circle is c, then the length of the arc is l, given by:

Theorem 7.9The area of a sector is given by the proportion where As is the area of the sector, Ac is the area of the circle and is the arc measure in degrees.

Example #1Find the arc length of the given circle.

Example #2Find the area of the sector.

Finding the area of a segmentTo find the area of a segment:1st find the area of the sector 2nd find area of the triangle that is formed by the two radii and the chord.3rd subtract the area of the sector form the area of the triangle.

Example #3Find the area of the segment.