Question

lesson 1: drilling for understanding

1. find the surface area of a sphere to the nearest whole number (and include units) if the radius of the sphere is

a. 5 cm
c. 184 mm

Explanation:

Step1: Recall surface - area formula

The formula for the surface area of a sphere is $A = 4\pi r^{2}$.

Step2: Solve for radius $r = 5$ cm

Substitute $r = 5$ into the formula: $A=4\pi(5)^{2}=4\pi\times25 = 100\pi\approx100\times 3.14159 = 314.159\approx314$ $cm^{2}$.

Step3: Convert 184 mm to cm

Since $1$ cm=$10$ mm, then $r = 18.4$ cm.

Step4: Solve for radius $r = 18.4$ cm

Substitute $r = 18.4$ into the formula: $A = 4\pi(18.4)^{2}=4\pi\times338.56\approx4\times3.14159\times338.56=4259.807\approx4260$ $cm^{2}$.

Answer:

a. $314$ $cm^{2}$
c. $4260$ $cm^{2}$