randRange(1, 8)

Suppose the radius of a circle is `\color{R_COLOR}{R}`. What is its area?

PI * R * R
initCircle( R ); drawRadius( R );
randRange(1, 8)

Suppose the diameter of a circle is `\color{D_COLOR}{2 * R}`. What is its area?

PI * R * R
initCircle( R ); drawDiameter( R );

First, find the radius:

`\begin{align} r &= \dfrac d2 \\ r &= \dfrac{\color{D_COLOR}{2 * R}}{2} \\ r &= \color{R_COLOR}{R} \end{align}`

randRange(1, 8)

Suppose the circumference of a circle is `\color{C_COLOR}{2 * R\pi}`. What is its area?

PI * R * R
initCircle( R ); drawCircumference( R );

First, find the radius:

`\begin{align} r &= \dfrac{c}{2\pi} \\ r &= \dfrac{\color{C_COLOR}{2 * R\pi}}{2} \\ r &= \color{R_COLOR}{R} \end{align}`

The equation for the area of a circle is:

`K = \pi r^2`

`K = \pi \cdot \color{R_COLOR}{R}^2`

`K = \color{K_COLOR}{R * R\pi}`

drawArea( R );