Final answer:
The area of a circle with a diameter of 1.8 cm and using π as 3.142 is approximately 2.5 cm² when rounded to 1 decimal place.
Step-by-step explanation:
To calculate the area of a circle when the diameter 1.8 cm, we first need to find the radius. Since the diameter is the full width of the circle, the radius, which is half the diameter, would be 1.8 cm ÷ 2 = 0.9 cm. Next, we use the formula for the area of a circle, A = πr².
With π approximately 3.142 and the radius being 0.9 cm, we get:
A = 3.142 × (0.9 cm)²
A = 3.142 × (0.81 cm²)
A = 2.54482 cm²
To give the answer to 1 decimal place, it would be approximately:
A = 2.5 cm²