Question

A given circle has an approximate area of 78.5 square units. How long is the circles diameter?

Answer 1

Remember that

The area of a circle is equal to

$A=\pi\cdot r^2$

we have

A=78.5 unit2

I will assume pi=3.14

substitute in the formula

$\begin{gathered} 78.5=3.14\cdot r^2 \\ r^2=\frac{78.5}{3.14} \\ r=5\text{ units} \end{gathered}$

the diameter is two times the radius

so

D=2(5)=10 units

therefore

The diameter is 10 units