Question

How do you find the area of a circle if the circumference of a circle is 28.26cm?

Answer 1

`"area "~~63.55" cm"^2`

Explanation:

`"the area (A) of a circle is given by"`

`•color(white)(x)A=pir^2larrcolor(blue)"r is the radius"`

`"to calculate A we require to find r"`

`"the circumference (C) of a circle is given by"`

`•color(white)(x)C=2pir`

`"here "C=28.26 " so equating"`

`2pir=28.26`

`"divide both sides by "2pi`

`(cancel(2pi) r)/cancel(2pi)=28.26/(2pi)`

`r=28.26/(2pi)larr" round on final step"`

`"substitute this value into formula for A"`

`A=pixx(28.26/(2pi))^2~~63.55" to 2 dec. places"`