my college hive icon mycollegehive
Groups
My College Hive notifiction icon Questions
Tags
Quiz
Books
The area enclosed between two concentric circles is 770 sq cm. If the radius of outer circle is 21cm. Find the radius of the inner circle.
CBSE class-10 math areas-related-to-circles
up
0
down

The area enclosed between two concentric circles is 770 sq cm. If the radius of outer circle is 21cm. Find the radius of the inner circle.

19 views
Share Follow
peter
Asked by peterrep:837
University of Lagos Nigeria
31 July 2020

Comments





1 answer(s)

james_mark
James_mark answeredrep:188
School not set Nigeria
31 July 2020
up
0
down

Area of a circle = πr2

where r is the radius

The area between the two circles is given as 770 sqcm.

If the radius of the outer circle is 21cm, it's area will be:

π(21)2 = 441π

Therefore, the area of the inner circle = 441π - 770

= 615.44 sqcm

Also, area = πr2

615.44 = πr2

divide both sides by π

r2 = 195.9

r = 14cm

Therefore, the radius of the inner circle is 14cm

Share
Comments






Your Answer

my college hive loader icon



Related Tags

CBSE

0 followers

56 questions

class-10

0 followers

56 questions

math

2 followers

985 questions