arc length

DEPARTMENT OF EDUCATIONDIVISION OF CITY SCHOOLS

ERNESTO RONDON HIGH SCHOOL

MATHEMATICSDEPARTMENT

Featuring: CIRCLE

THE DOODLE GAME

an unfocused drawing made while a person's attention is otherwise occupied. Doodles are simple

drawings that can have concrete representational meaning or may

just be abstract shapes.

*DOODLE

http://en.wikipedia.org/wiki/Drawing

http://en.wikipedia.org/wiki/Abstract_art

GUESS MY FIGURE 543210

MEXICAN FRYING AN EGG

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A TAHO VENDOR

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AN ICE SCREAM VENDOR

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MEXICAN PLAYING A TRUMPET

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MEXICAN RIDING A BICYCLE

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MEXICAN TAKING A BATH

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MEXICAN COUPLE KISSING

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GIRAFFE PASSING BY THE WINDOW

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KOALA BEAR CLIMBING A TREE

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THREE MEXICANS PEEING

RECALL

How do you call on the distance between the center and a point on the circle?

RECALL

How do you call on the angle whose vertex is at the center and whose sides are the radii of the circle?

RECALL

How do you call on a subset /any part of a circle.

ARCARC

RADIUSCENTRAL ANGLECENTRAL ANGLE

RADIUS

ARC LENGTH

ARC LENGTHit refers to the fractional part of the circumference subtended by the arc in a circle. Radian

measure is used to find the arc length.

GROUP ACTIVITY NO. 4

You are given 7 minutes to answer the activity. Speed and accuracy are

important.

09000 7 87654321560 04 98765432103 9876543210987654321021 987654321098765432100Hours Minutes Seconds

A

BC

D

E

FG

H

45°

A

B

45°

The arc length (s) is directly proportional to the radius (r) of the circle. While the central angle (Ѳ) is constant.

In equation:s /r = Ѳ

where:s – arc length of the circler – radius of the circleѲ – central angle in

radian measure

s = Ѳ•r

1. Find arc length (s) of the circle illustrated below.

SAMPLE EXERCISE

π/35cms

π/35cm s SOLUTION:s = ѳ • r = π/3 • 5 = 5π/3

ANSWER: s = 5π/3 cm.

2. Find arc length (s) of the circleSAMPLE EXERCISE

100°7cms

SOLUTION:

s = ѳ • r = 5π/9 • 7 = 35π/9

ANSWER: s = 35π/9 cm.

100°7cms

Change the central angle to radian measure

100° x π/180 °5π/9

3. The radius of the circle is 25mm. Find the length of an arc of the circle subtended by a central of 60°.

SAMPLE EXERCISE

SOLUTION:s = ѳ • r = π/3 • 25 = 25π/3mm

60° x π/180 °π/3

SUMMING UP!

What have added inside the coconut shell?

Quiz no. 5Find the arc length of a circle having the radius r and central angle with measure Ѳ.

1. r = 4 feet, Ѳ = π/42. r = 6inches, Ѳ = 330°3. r= 10meters , Ѳ = 150°

ASSIGNMENT

3.82 m

R

Q

P

7.64 in.

18 in.

Z

Y

X

Find the circumference

Find the central angle

Thank You

arc length

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