Answer:
Explanation:
Hi, is this really a college-level question?
Anyway, do you remember the formula for the area of a circle?
A = π r²
You know what pi is, 3.141.
And you know what r is. Oh, they didn't give us r? Well isn't it half of d? So it's 115mm.
Plug in and solve:
A = 3.141 x (115)² = 3.141 x 13,225 = 41, 540 mm²
But that's an awfully big number, so convert it to cm² by dividing by 100: 41,540 mm² = 415 cm²
(That works because there are 10 mm in a cm of course, and when you square 10 you get 100. You could've also converted the 230 mm right up front to 23 cm and gotten the same answer.)