Problem
Area - Circumference Given: $\overline{A C}$ is a diàmeter $\mathbf{A O}$ is a radius BD is a diameter OD is a radius \[ O A=5 \] 1. What is the area of the circle? 2. What is the circumference of the circle? 3. How does the area of the small sector $A B O$ compare to the area of the circle? 4. How does the length of arc CD compare to the circumference of the circle?
Solution
Step 1 ：Given that the radius of the circle is 5 units, we can calculate the area of the circle using the formula \(\pi r^2\).
Step 2 ：Substitute the given radius into the formula: \(\pi (5)^2\).
Step 3 ：Calculate the area to get approximately 78.54 square units.
Step 4 ：Final Answer: The area of the circle is \(\boxed{78.54}\) square units.
