Question

find the circumference of a circle whose area is 4 times the area of a circle with diameter 21 CM​

Answer 1

Answer:

132 cm

Step-by-step explanation:

diameter of smaller circle = 21cm

radius = 21/2 cm

area of smaller circle = (22/7)(21/2)^2 = 693/2 sq.cm

now area of big circle = 4 x area of smaller circle = 4 x693/2 = 1386 sq.cm

let the radius of big cirle be r cm

=> πr∧2 = 1386

⇒ r∧2 = 1386 x7/22

⇒r∧2 = 441

⇒r = 21 cm

circumference of big circle = 2πr = 2 x(22/7)x21 = 132cm

Answer 2

Answer:

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