The first one is 31.875 and the second is 12 I don't know how to explain to get it. Sorry
Answer:
C (circumference) =2×π×r
we've got a 30-60-90 triangle
which means 9=d√3, d=5.19 exact inches
or ≈5.20 inches
d=2r, r=5.20÷2≈2.60 inches
C=2×3.14×2.60≈16.328
Yes, his estimate is reasonable. But only if Michael is less than 2 years old.
