Step-by-step explanation:
Arc length formula is
[tex]s = rx[/tex]
where x is radinas.
A semi circle has a radian measure of
[tex]\pi[/tex]
The radius is half of the diameter, 12 so the radius is
[tex]12 \times \frac{1}{2} = 6[/tex]
So the arc length is
[tex]6 \times \pi = 6\pi[/tex]
Area of semi circle is
[tex] \frac{1}{2} \pi {r}^{2} [/tex]
where r is the radius.
[tex] \frac{1}{2} \pi6 {}^{2} [/tex]
[tex] \frac{1}{2} 36\pi[/tex]
[tex]18\pi[/tex]
