Question

find the area of a ring lying between the circumference of two concentric circles whose radii are 10.5 cm and 7 cm.

Answer 1

You can apply the formula to find area of a ring i.e. 22/7(R^2 -r^2)
Then
22/7 (10.5^2 -7^2)
= 192.5 cm^2

Answer 2

Dear Student,

◆ Answer -

∆A = 192.5 cm^2

● Explanation -

Area of small circle is -

A1 = πr1^2

A1 = 22/7 × 7^2

A1 = 154 cm^2

Area of big circle is -

A2 = πr2^2

A2 = 22/7 × 10.5^2

A2 = 346.5 cm^2

So now, area of a ring lying between two circles is -

∆A = A2 - A1

∆A = 346.5 - 154

∆A = 192.5 cm^2

Hence, the area of a ring lying between the circumference of two concentric circles is 192.5 cm^2.

Thanks dear. Hope this helps you...