Question

The perimeter of a semicircular disc is 72cm. Find the radius of the disc​

Answer 1

14 cm

Explanation:

To find:-

• Radius of the disc .

Answer:-

We are here given that the perimeter of a semicircular disc is 72cm . We are interested in finding out the radius of the disc. Perimeter of a semicircular disc is given by,

`:\implies \sf P = \pi r + 2r \\`

where r is the radius of the disc

Now on substituting the respective values, we have;

`:\implies \sf 72cm = \pi r + 2r \\`

`:\implies \sf 72cm = r(\pi + 2)\\`

`:\implies \sf r =(72)/(\pi+2) cm \\`

`:\implies \sf r =(72)/(3.14+2) cm \\`

`:\implies \sf r = (72)/(5.14)\\`

`:\implies \sf \pink{radius= 14.007\ cm } \\`

Hence the radius of the semicircular disc is approximately 14 cm .

Answer 2

The radius is approximately 14.003.

Explanation:

Given:

• Perimeter = 72

Formulas for the semicircle:

• d = 2 r
• a = π r
• p = π r + 2 r
• S = π r2 / 2