Question

The diameter of a circle is 42 cm, find its perimeter. If the perimeter of the circle is doubled, what will be the radius of the new circle, take pi = 22/7

Answer 1

Given: d = 42 cm

r = d/2 = 42/2 = 21 cm

Perimeter = 2Π r

= 2x 22/7 ×21 = 132 cm

Perimeter doubled means 2 time perimeter = 2 × 132 = 264 cm

To find radius:

Perimeter = 2Πr

264 = 2 × 22/7 × r

r = (264×7)/(2×22)

=1848/44

= 42

r = 42 cm

Note:

From this we understand that when perimeter doubles radius also doubles or vice versa

Hope this is helpful