Question

find the circumference of each circle to help crack the code and answer the did you know? question below (answers to 1dp)
a (circle with diameter 5) 15.7
b (circle with diameter 8) 25.1
c (circle with diameter 3.7) 11.6
d (circle with diameter 11) 34.6
e (circle with diameter 10) 31.4
f (circle with diameter 2.9) 9.1
g (circle with radius 6) 37.7
h (circle with radius 9) 56.5
i (circle with radius 8.2) 51.5
j (circle with radius 4.4) 27.6
k (circle with radius 12) 75.4
l (circle with radius 7.5) 47.1
m (circle with diameter 20.5) 64.4
n (circle with radius 10) 62.8
o (circle with radius 9.3) 58.4
p (circle with diameter 17) 53.4
q (circle with radius 15) 94.2
r (circle with diameter 15.7) 49.3

Explanation:

Step1: Recall circumference formulas

Circumference: $C = \pi d$ or $C = 2\pi r$, where $d$ = diameter, $r$ = radius.

Step2: Calculate Circle D (d=11)

$C = \pi \times 11 \approx 34.56 \approx 34.6$

Step3: Calculate Circle E (d=10)

$C = \pi \times 10 \approx 31.42 \approx 31.4$

Step4: Calculate Circle F (d=2.9)

$C = \pi \times 2.9 \approx 9.11 \approx 9.1$

Step5: Calculate Circle G (d=6)

$C = \pi \times 6 \approx 18.85 \approx 18.9$

Step6: Calculate Circle H (d=9)

$C = \pi \times 9 \approx 28.27 \approx 28.3$

Step7: Calculate Circle I (d=8.2)

$C = \pi \times 8.2 \approx 25.76 \approx 25.8$

Step8: Calculate Circle J (d=4.4)

$C = \pi \times 4.4 \approx 13.82 \approx 13.8$

Step9: Calculate Circle K (d=12)

$C = \pi \times 12 \approx 37.70 \approx 37.7$

Step10: Calculate Circle L (d=7.5)

$C = \pi \times 7.5 \approx 23.56 \approx 23.6$

Step11: Calculate Circle M (d=20.5)

$C = \pi \times 20.5 \approx 64.40 \approx 64.4$

Step12: Calculate Circle N (d=10)

$C = \pi \times 10 \approx 31.42 \approx 31.4$

Step13: Calculate Circle O (d=9.3)

$C = \pi \times 9.3 \approx 29.22 \approx 29.2$

Step14: Calculate Circle P (d=17)

$C = \pi \times 17 \approx 53.41 \approx 53.4$

Step15: Calculate Circle Q (d=15)

$C = \pi \times 15 \approx 47.12 \approx 47.1$

Step16: Calculate Circle R (d=15.7)

$C = \pi \times 15.7 \approx 49.32 \approx 49.3$

Answer:

• D: 34.6
• E: 31.4
• F: 9.1
• G: 18.9
• H: 28.3
• I: 25.8
• J: 13.8
• K: 37.7
• L: 23.6
• M: 64.4
• N: 31.4
• O: 29.2
• P: 53.4
• Q: 47.1
• R: 49.3

(Note: Pre-filled circles A-C match the 1 dpi calculation: A: $\pi \times5\approx15.7$, B: $\pi \times8\approx25.1$, C: $\pi \times3.7\approx11.6$)