Answer:
I will let you answer this after reading below
Step-by-step explanation:
a=area
[tex] a = \pi {r}^{2} [/tex]
[tex]r = d \div 2[/tex]
write a in terms of d
[tex] a = \frac{\pi {d}^{2}}{ 4}[/tex]
since it's a semicircle divide a by 2 and that's your answer
I can confirm you answer if you like in a comment