Question

area & circumference riddle sheet
why was sir cumference the roundest knight at king arthurs table?
complete each question. use 3.14 for pi. find the answer at the bottom of the page and then write the letter that corresponds to that correct answer on the line above it.
h find the circumference:
o find the area of a circle with a radius of 30 mm.
o find the area:
t find the circumference:
e find the area of a circle with a diameter of 12 feet.
a find the area of a circle with a radius of 7 inches.
p a circle has a diameter of 95 mm. what is the distance around the circle?
m find the circumference:
e a circle measures 16 inches across. how much space does the circle fill?
t find the circumference of a circle with a radius of 7.5 meters.
h find the area:
c find the circumference:
i find the area of a circle with a diameter of 10 cm.
u the radius of a circle is 40 inches. find the circumference.
because
376.8 113.04 153.86 36.11 200.96 47.1 2,826 314 408.2 251.2 62.8 452.16 298.3 78.5

Explanation:

H: Find the circumference (diameter = 20 mm)

Step1: Use the circumference formula \(C=\pi d\)

Given \(d = 20\) mm and \(\pi=3.14\), then \(C = 3.14\times20=62.8\) mm

O: Find the area of a circle with radius \(r = 30\) mm

Step1: Use the area formula \(A=\pi r^{2}\)

\(A=3.14\times30^{2}=3.14\times900 = 2826\) \(mm^{2}\)

O: Find the area (diameter \(d = 20\) in, so radius \(r=\frac{d}{2}=10\) in)

Step1: Use the area formula \(A=\pi r^{2}\)

\(A = 3.14\times10^{2}=314\) \(in^{2}\)

T: Find the circumference (diameter \(d = 15\) cm, so \(C=\pi d\))

Step1: Substitute values

\(C=3.14\times15 = 47.1\) cm

E: Find the area of a circle with diameter \(d = 12\) feet (radius \(r=\frac{d}{2}=6\) feet)

Step1: Use the area formula \(A=\pi r^{2}\)

\(A=3.14\times6^{2}=3.14\times36=113.04\) \(ft^{2}\)

A: Find the area of a circle with radius \(r = 7\) inches

Step1: Use the area formula \(A=\pi r^{2}\)

\(A=3.14\times7^{2}=3.14\times49 = 153.86\) \(in^{2}\)

P: Distance around the circle (circumference, \(d = 95\) mm, \(C=\pi d\))

Step1: Substitute values

\(C=3.14\times95=298.3\) mm

M: Find the circumference (diameter \(d = 65\) m, \(C=\pi d\))

Step1: Substitute values

\(C=3.14\times65 = 204.1\) (This might be a mis - check. If radius \(r = 65\) m (assuming a typo in the problem statement, if it's radius \(r\), then \(C = 2\pi r=2\times3.14\times65=408.2\) m)

E: A circle measures 16 inches across (diameter \(d = 16\) inches, radius \(r = 8\) inches, find area \(A=\pi r^{2}\))

Step1: Substitute values

\(A=3.14\times8^{2}=3.14\times64 = 200.96\) \(in^{2}\)

T: Find the circumference of a circle with radius \(r = 7.5\) meters (\(C = 2\pi r\))

Step1: Substitute values

\(C=2\times3.14\times7.5=47.1\) m

H: Find the area (diameter \(d = 12\) mm, radius \(r = 6\) mm, \(A=\pi r^{2}\))

Step1: Substitute values

\(A=3.14\times6^{2}=3.14\times36=113.04\) \(mm^{2}\)

C: Find the circumference (diameter \(d = 10\) cm, \(C=\pi d\))

Step1: Substitute values

\(C=3.14\times10 = 31.4\) (If radius \(r = 10\) cm (assuming a typo), then \(C=2\pi r=2\times3.14\times10 = 62.8\) cm)

I: Find the area of a circle with diameter \(d = 10\) cm (radius \(r = 5\) cm, \(A=\pi r^{2}\))

Step1: Substitute values

\(A=3.14\times5^{2}=78.5\) \(cm^{2}\)

U: Radius \(r = 40\) inches, find circumference (\(C = 2\pi r\))

Step1: Substitute values

\(C=2\times3.14\times40=251.2\) inches

Answer:

For each problem:

• H (d = 20 mm): \(62.8\)
• O (r = 30 mm): \(2826\)
• O (d = 20 in): \(314\)
• T (d = 15 cm): \(47.1\)
• E (d = 12 ft): \(113.04\)
• A (r = 7 in): \(153.86\)
• P (d = 95 mm): \(298.3\)
• M (assuming radius \(r = 65\) m): \(408.2\)
• E (d = 16 in): \(200.96\)
• T (r = 7.5 m): \(47.1\)
• H (d = 12 mm): \(113.04\)
• C (assuming r = 10 cm): \(62.8\)
• I (d = 10 cm): \(78.5\)
• U (r = 40 in): \(251.2\)