The circle shown at right has a diameter of $20$ cm.

1. What measurement do you need to find in order to calculate the area inside the circle?

   Hint (a):

   Recall the equation for area from the Math Notes box of Lesson 5.3.4.
   $A = r^2 π$

   More Help (a):

   What measurement is missing in this equation?
   

2. Find the area inside the circle using the formula $A = r^2 π$. Write your answer as a product of $r^2$ and $π$, and as an approximation using $π ≈ 3.14$.

   Step 1(b):

   Diameter $= 2$ (radius)
   Solve for $r$.

   Step 2(b):

   Substitute the newly calculated radius into the area formula.
   $20 = 2 r$
   $A = (10)^2 π$

   Answer (b):

   $314$ cm^{$^{2}$}