Question

find the circumference of a circle whose diameter is4.2​

Answer 1

diameter is 4.2, => d= 2r, r= d/2, r= 4,2= 2,1 (radius)

circumference is 2πr= 2•π•2,1= 4.2π cm

Answer 2

here is your answer,

let the radious of this circle is x .

according to the question,

2x = 4.2

or, x= 4.2/2 = 2.1

the circumference of this circle is

2 pai x = 2×22/7×2.1 =13.2

hope it helps you.