Let’s solve each problem step by step.
We know the formula for circumference of a circle is:
Circumference = π × diameter
or
Circumference = 2 × π × radius
Since all answers must be “in terms of π”, we just leave π in the answer — no need to multiply by 3.14.
---
Problem 1:
Circle with radius = 13 m
→ Diameter = 2 × 13 = 26 m
→ Circumference = π × 26 =
26π m
---
Problem 2:
Circle with radius = 18 (units not given, but same as others)
→ Diameter = 2 × 18 = 36
→ Circumference = π × 36 =
36π
---
Problem 3:
Circle with diameter = 20 in
→ Circumference = π × 20 =
20π in
---
Problem 4:
Circle with radius = 17 ft
→ Diameter = 2 × 17 = 34 ft
→ Circumference = π × 34 =
34π ft
---
Problem 5:
Circle with diameter = 27 cm
→ Circumference = π × 27 =
27π cm
---
Problem 6:
Circle with radius = 2.8 km
→ Diameter = 2 × 2.8 = 5.6 km
→ Circumference = π × 5.6 =
5.6π km
---
Problem 7:
Bike wheel has diameter = 10 in
→ Circumference = π × 10 =
10π in
---
Problem 8:
Minute hand = 16 in long → this is the
radius of the circle it traces.
In one hour, the tip goes around the whole circle once → so distance = circumference.
→ Radius = 16 in → Diameter = 32 in
→ Circumference = π × 32 =
32π in
---
Final Answer:
1) 26π m
2) 36π
3) 20π in
4) 34π ft
5) 27π cm
6) 5.6π km
7) 10π in
8) 32π in
Parent Tip: Review the logic above to help your child master the concept of circle area and circumference worksheet.
