Transcript 6.7 Circumference and Arc Length

6.7
Circumference and Arc Length
6.7-6.8 Quiz: Friday
6.5-6.8 Test: Nov. 30
Performance Final: Dec. 2
6.9 Quiz: Dec. 7 (maybe!)
Vocabulary:
• The circumference of a circle is the
distance around the circle.
(length around the circle)
• Theorem 6.19: Circumference of a Circle
– The circumference C of a circle is C = πd or
C = 2πr, where d is the diameter of the circle
and r is the radius of the circle.
d
2 r
Example 1:
• Find the indicated measure
1) Circumference of a circle with radius of
11 meters.
2) Circumference of a circle is 18 yards,
find the radius.
You Try:
1) Find the circumference of a circle with a
diameter of 23 inches.
2) Find the diameter of a circle with
circumference 75 meters.
3) Find the radius of a circle with
circumference 35 yd.
Vocabulary:
• An arc length is a proportion of the
circumference of a circle.
• Arc Length Corollary
– In a circle, the ratio of the length of a given
arc to the circumference is equal to the ratio
of the measure of the arc to 360o
arc
length 
 circumference
360
Example 2:
• Find the indicated arc length
a) Arc length of AB
b)
arc
length 
 circumference
360
You Try:
Last two
1) Find the length of arc AB.
2) Find the radius of circle N.
Classwork/Homework
• P. 226 #1-18 ALL
What we have left:
• 6.7-6.8 Quiz: Friday
• 6.5-6.8 Test: Nov. 30
• Performance Exam: Dec. 2
• 6.9 Quiz: Dec. 7 (maybe!)
Practice Practice Practice! You don’t
want your average to drop!