Please look at the photo.

It's 144 pi.

Step-by-step explanation:

12 feet is the radius, and 12 x 12 is 144.  Leaving it in terms of pi means to leave the pi alone, and not to multiply it.

13

step-by-step explanation:

distance formula is d=√(x2-x1)^2   +   (y2-y1)^2

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)