Question

the diameter d of a sphere is 18.2 mm. calculate the spheres surface area a. use the value 3.14 for π, and round your answer to the nearest tenth. a = mm²

Explanation:

Step1: Find radius from diameter

The radius $r$ is half the diameter.
$r = \frac{D}{2} = \frac{18.2}{2} = 9.1$ mm

Step2: Apply surface area formula

The surface area of a sphere is $A = 4\pi r^2$.
Substitute $\pi=3.14$ and $r=9.1$:
$A = 4 \times 3.14 \times (9.1)^2$

Step3: Calculate $r^2$ first

$9.1^2 = 82.81$

Step4: Compute intermediate product

$4 \times 3.14 = 12.56$

Step5: Find final area before rounding

$A = 12.56 \times 82.81 = 1039.0936$

Step6: Round to nearest tenth

Round 1039.0936 to one decimal place.
$A \approx 1039.1$

Answer:

1039.1 mm²