Question

A semi-circle has a diameter of 32cm there is a another hole which is a semi-circle with a diameter of 16cm .Find the perimeter of the bigger semi-circle.(Take PI as 22/7)​

Answer 1

Perimeter of Circles

Perimeter of the object is 91.4285 cm

Explanation:

The perimeter of a circle is defined as
`2\pi r`

The perimeter of outer arc will be
`2\pi r_(1) /2\\`

The perimeter of inner arc will be
`2\pi r_(2) /2\\`

Where
`r_(1\\)` is radius of bigger semicircle and
`r_(2)` is radius of smaller semicircle

Given diameter of outer semicircle = 32 cm

`r_(1\\)` = 32/2 = 16 cm

Given diameter of outer semicircle = 16 cm

`r_(2\\)\\` = 16/2 = 8 cm

So the perimeter of the object =
`\pi r_(1) +\pi r_(2) + 2 (r_(1) -r_(2) )`

Perimeter P = 22/7 * (16 +8 ) + 2 * 8 =

P = 22/7 * 24 +16

So P = 75.4285 +16 = 91.4285 cm