Question

If the area of the circle is 81tt, find its circumference in terms of tt

Answer 1

area=πr²

given

area=81π

81π=πr²

divide both sides by π

81=r²

sqrt both sides

9=r

circumfere=2πr

we know that r=9 so

2π9=18π

answer is B. 18π

Answer 2

area=πr²
given
area=81π
81π=πr²
divide both sides by π
81=r²
sqrt both sides
9=r

circumfere=2πr
we know that r=9 so
2π9=18π
answer is B. 18π