Question

Calculate the area and perimeter of ring where a=7cm b=14cm

Answer 1

Area of ring = 462 cm²

Perimeter of ring = 44 cm

Explanation:

Given,

radius of inner ring = 7 cm

radius of outer ring = 14 cm

To find,

Area and perimeter of ring

Formula:

Area of circle = π Radius²

Perimeter of circle = 2π Radius

Area of inner ring = π Radius²

⇒
`(22)/(7)` ×
`7^(2)`

⇒ 22 × 7

⇒ 154 cm²

Area of outer ring = π Radius²

⇒
`(22)/(7)` ×
`14^(2)`

⇒ 22 × 14 × 2

⇒ 616 cm²

∴ Area of ring = 616 - 154 = 462 cm²

Perimeter of inner ring = 2π Radius

⇒ 2 ×
`(22)/(7)` × 7

⇒ 44 cm

Perimeter of outer ring = 2π Radius

⇒ 2 ×
`(22)/(7)` × 14

⇒ 88 cm

∴ Perimeter of ring = 88 - 44 = 44 cm