Grade 7 Math · Spatial Sense

Surface area of a cylinder

Use a cylinder's net (two circles plus a rectangle) to find its total surface area, using pi approx. 3.14. Unlimited questions, five difficulty levels, and a full worked solution every time — free.

Practice this skill Curriculum: G7-E2.6

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A cylindrical rain barrel has a radius of 3 m and a height of 10 m. Using pi = 3.14, what is its total surface area (both circular ends included)?

Answer: 244.92

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A cylindrical thermos has a radius of 6 cm and a height of 11 cm. Using pi = 3.14, what is its total surface area (both circular ends included)?

📘 Worked solution
1Two circular ends: 2 · π · r2 = 2 · 3.14 · 62 = 226.08 cm2A cylinder's net has two identical circles -- one for each end.
2Curved side (unrolled): π · d · h = 3.14 · 12 · 11 = 414.48 cm2Unroll the curved surface -- it becomes a rectangle whose width is the circle's circumference and whose height is the cylinder's height.
3226.08 + 414.48 = 640.56 cm2Add the areas of all three net pieces together for the total surface area.

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