THE AREA OF A CIRCLE:
Circle - a closed curved figure with equal radius.
or
A =π (D/2)2
where D = diameter; D = r/2
or
A = π (D2/4)
where:
A = area
pi = π = 3.1416
r = radius
r2 = square of
a radius
D = Diameter
Note:
You have to find the given first so that it would be easy for you to substitute. See example below.
Example:
1. Find the Area of a circle whose radius ( r ) is 5 meters.
Given:
r = 5 meters or simply m
π = 3.1416
Required: Area
Solution:
A = πr2 , then..
A = 3.1416 * (5m)(5m) = 78.54 square-meter ; final answer
2. The diameter of a hula hoop measures 2 feet. Find the its area.
Given:
D = 2 ft.
Required: Area
Solution:
A =π (D/2)2
A = π (D/2)2
= π (2 ft / 2)2
= π ( 1 ft )2
= π ft 2 ; final answer
2. What is the area of a circle if its diameter measures 4 meters?
D = 4 m.
Required: Area
Solution:
A =π (D/2)2
A = π (D/2)2
= π (4m / 2)2
= 4π square meter = 4π m2 ; final answer
D = Diameter
Note:
You have to find the given first so that it would be easy for you to substitute. See example below.
Example:
1. Find the Area of a circle whose radius ( r ) is 5 meters.
Given:
r = 5 meters or simply m
π = 3.1416
Required: Area
Solution:
A = πr2 , then..
A = 3.1416 * (5m)(5m) = 78.54 square-meter ; final answer
2. The diameter of a hula hoop measures 2 feet. Find the its area.
Given:
D = 2 ft.
Required: Area
Solution:
A =π (D/2)2
A = π (D/2)2
= π (2 ft / 2)2
= π ( 1 ft )2
= π ft 2 ; final answer
2. What is the area of a circle if its diameter measures 4 meters?
Given:
D = 4 m.
Required: Area
Solution:
A =π (D/2)2
A = π (D/2)2
= π (4m / 2)2
= π ( 2 m )2
= 4π square meter = 4π m2 ; final answer
