Find the circumference of a circle whose radius is 14 cm, and whose diameter is 49 cm.

Circumference of a circle with radius 14 cm

Step 1: Formula for circumference
$C = 2\pi r$

Step 2: Substitute $r = 14~\mathrm{cm}$
$C = 2\pi \times 14~\mathrm{cm}$

Step 3: Simplify
$C = 28\pi~\mathrm{cm}$

28\pi~\mathrm{cm}

Circumference of a circle with diameter 49 cm

Step 1: Formula for circumference
$C = \pi d$

Step 2: Substitute $d = 49~\mathrm{cm}$
$C = \pi \times 49~\mathrm{cm}$

Step 3: Simplify
$C = 49\pi~\mathrm{cm}$

49\pi~\mathrm{cm}

Area of a circle with radius 12 cm

Step 1: Formula for area
$A = \pi r^{2}$

Step 2: Substitute $r = 12~\mathrm{cm}$
$A = \pi (12~cm)^{2}$

Step 3: Simplify
$A = \pi \times 144~cm^{2}$
$A = 144\pi~cm^{2}$

144\pi~\mathrm{cm^{2}}