To calculate the area of a circle, we use the formula:

$A = \pi r^2$

Where:

• $A$ is the area of the circle,
• $\pi$ is approximately 3.14 (as per your instruction),
• $r$ is the radius of the circle.

Given that the diameter of the circle is 4 units, we first need to find the radius. The radius is half of the diameter:

$r = \frac{4}{2} = 2 \, \text{units}$

Now, using the formula for the area:

$A = 3.14 \times (2)^2 = 3.14 \times 4 = 12.56 \, \text{square units}$

Rounding to one decimal place:

$A \approx 12.6 \, \text{square units}$

So, the area of the circle is approximately 12.6 square units.

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Would you like further details or clarifications on this? Here are a few related questions:

1. How do you find the circumference of a circle?
2. What if the radius was 3 units instead of 2 units, how would the area change?
3. How is the value of $\pi$ used in real-world applications?
4. How does the formula for the area of a circle differ from the area of a square?
5. What is the formula to calculate the volume of a sphere?

Tip: Remember that the radius is always half of the diameter in a circle!