Math Expression: Area of a Circle Practice Question

Given a circle with the radius of 5cm. Find the circumference of this circle. Take π as 3.14.

Step 1

The picture below shows the circle with the radius of 5cm. d.
Step 2

To calculate the area, we can start with the formula for the area of a circle:
Step 3

Since the radius is given as 5cm, we can substitute r with 5. Similarly, we can substitute π with 3.14. After doing so, we can calculate for A, as shown below:
Step 4

Now, the calculated number 78.5 only has meaning if we include the unit for it. Since the radius is in cm, the unit for the area will be cm². Hence:

A = 78.5 cm²
Step 5

Clearly, the answer is B.