1. CIRCLE
1. Basic terms
Radius (jari-jari) : any segment that joins the center to a point of the circle
Chord (tali busur): a segment that joins two points of the circle
Diameter (diameter) : is chord that contains the center of a circle
Arc (busur) : is part of a circle
Apotema (apotema) : is the distance from center to chord (it must perpendicular to chord)
Segment (tembereng) : an area bounded by chord and an arc of the circle
Sector (juring) : an area bounded by two radii and an arc of the circle
Example
Radius : OA, OB, OC, OD, OE, OF
Arc B
Sector C
Chord : FE, AF, AD
Diameter : AD
Arc : O A  D
Apotema : OG G
Segment : FE E
Sector : OBC
Segment F
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Created by ﺠﯿﻄ for mathlabsky.wordpress.com

2. 2. Circumference and Area of Circles
Formula:
Circumference (Keliling) or
Area (Luas) or
C = Circumference
A = Area
D = Diameter
r = Radius
D = 2 r

3. Example : find the circumference and area of a circle with the given radius or diameter
1. r = 21 cm
2. D = 20 cm

4. Exercise
1. Find the circumference and area of a circle with the radius or diameter .
a. r = 28 cm
b. D = 30 cm
2. Find the radius of a circle with the given area.
a. A = 36 cm2
b. A = 6,25 cm2
3. The area of a circles is cm2. Find the circumference.
4. Find the radius of a circle with the given circumference.
a. C = 2 cm
b. C = 25 cm

5. Find the circumference and area of each shaded region
7 cm a. b.
7 cm
15 cm d.
10 cm c.
20 cm e.
7 cm  f.
3 cm
2 cm
Annulus
Click the shape to solve

6. 7 cm a. I
Circumference =
= 18 cm

7. b.
7 cm
15 cm

8. I c.
20 cm II
III
Circumference = 62,8 cm

9. d.
10 cm

10. I e.
7 cm II
III
Circumference = 44 cm

11.  f.
3 cm
2 cm
Annulus