The radius of a circular disc is 21 cm.A circular piece of the disc is cut out from it.The radius of the remaining disc is 7 cm.What is the area of the disc that has been cut out?
Answers
Given : The radius of a circular disc is 21 cm.
A circular piece of the disc is cut out from it.
The radius of the remaining disc is 7 cm.
To Find : What is the area of the disc that has been cut out
Solution:
radius of a circular disc is 21 cm.
Area of circular Disc = π (21)² cm²
The radius of the remaining disc is 7 cm.
=> Area of remaining Disc = π (7)² cm²
area of the disc that has been cut out = π (21)² - π (7)²
= π ((21)² - (7)² )
= π ( 21 + 7) (21 - 7)
= π (28)(14)
π = 22/7
= (22/7) (28)(14)
= 22 * 28 * 2
= 22 * 56
= 1232 cm²
area of the disc that has been cut out= 1232 cm²
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Answer:
hope it help this is the answer
Step-by-step explanation:
you should remember 2πr is for circumference
and πr² is for area
for answer see the image
