Question

If the arean of circle is 56 what is radius??

Answer 1

The radius of the circle is `sqrt(A/pi)~~4.2`.

Explanation:

The area of a circle is given by `pir^2`, where `r` is the radius of the circle. We know what the area is, and `pi` is a constant, so we can solve for the radius:

`A=pir^2rarr56=pir^2rarrr^2=56/pirarrr=+-sqrt(56/pi)~~4.2`.

(We know we have to use the positive square root because a negative radius wouldn't make sense!)

Answer 2

`r=2sqrt(14pi)/(pi)~~4.22`

Explanation:

`A_"circle" = pir^2`

`56 = pir^2`

`56/pi = r^2`

`+-sqrt(56/pi) = sqrt(r^2)`

We can ignore the negative solution because a radius cannot be negative.

`r=2sqrt(14pi)/(pi)`

`r=2sqrt(14pi)/(pi)~~4.22`