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Surface Area of Cones — Easy Worksheet 1
Grade 8 · MathSheets Name: ____________________ Date: __________
Use π ≈ 3.14 unless the problem says "in terms of π". l is the slant height.
How to solve
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Example
A cone has a radius of 1 in and a slant height of 2 in. Find its surface area in square inches. Use π ≈ 3.14.
Answer: 9.42
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 8 = 40π. Add them: 25π + 40π = 65π. Use π ≈ 3.14: 65 × 3.14 = 204.1. The answer is 204.1 square centimeters.
✓ Correct!
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 8 = 40π. Add them: 25π + 40π = 65π. Use π ≈ 3.14: 65 × 3.14 = 204.1. The answer is 204.1 square centimeters.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 3 ft and a slant height of 6 ft. Find its surface area in square feet. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 7 = 35π. Add them: 25π + 35π = 60π. Use π ≈ 3.14: 60 × 3.14 = 188.4. The answer is 188.4 square feet.
✓ Correct!
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 7 = 35π. Add them: 25π + 35π = 60π. Use π ≈ 3.14: 60 × 3.14 = 188.4. The answer is 188.4 square feet.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 3 in and a slant height of 8 in. Find its surface area in square inches. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 5 = 5π. Add them: π + 5π = 6π. Use π ≈ 3.14: 6 × 3.14 = 18.84. The answer is 18.84 square meters.
✓ Correct!
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 5 = 5π. Add them: π + 5π = 6π. Use π ≈ 3.14: 6 × 3.14 = 18.84. The answer is 18.84 square meters.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 4 m and a slant height of 9 m. Find its surface area in square meters. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 22 = 4π. Curved side: π × 2 × 5 = 10π. Add them: 4π + 10π = 14π. Use π ≈ 3.14: 14 × 3.14 = 43.96. The answer is 43.96 square meters.
✓ Correct!
Not quite. The answer is
💡 Base: π × 22 = 4π. Curved side: π × 2 × 5 = 10π. Add them: 4π + 10π = 14π. Use π ≈ 3.14: 14 × 3.14 = 43.96. The answer is 43.96 square meters.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 1 cm and a slant height of 5 cm. Find its surface area in square centimeters. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 3 = 3π. Add them: π + 3π = 4π. Use π ≈ 3.14: 4 × 3.14 = 12.56. The answer is 12.56 square inches.
✓ Correct!
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 3 = 3π. Add them: π + 3π = 4π. Use π ≈ 3.14: 4 × 3.14 = 12.56. The answer is 12.56 square inches.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 5 m and a slant height of 7 m. Find its surface area in square meters. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 9 = 45π. Add them: 25π + 45π = 70π. Use π ≈ 3.14: 70 × 3.14 = 219.8. The answer is 219.8 square feet.
✓ Correct!
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 9 = 45π. Add them: 25π + 45π = 70π. Use π ≈ 3.14: 70 × 3.14 = 219.8. The answer is 219.8 square feet.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 3 in and a slant height of 7 in. Find its surface area in square inches. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 7 = 35π. Add them: 25π + 35π = 60π. Use π ≈ 3.14: 60 × 3.14 = 188.4. The answer is 188.4 square inches.
✓ Correct!
Not quite. The answer is
💡 Base: π × 52 = 25π. Curved side: π × 5 × 7 = 35π. Add them: 25π + 35π = 60π. Use π ≈ 3.14: 60 × 3.14 = 188.4. The answer is 188.4 square inches.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 5 ft and a slant height of 10 ft. Find its surface area in square feet. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 3 = 3π. Add them: π + 3π = 4π. Use π ≈ 3.14: 4 × 3.14 = 12.56. The answer is 12.56 square centimeters.
✓ Correct!
Not quite. The answer is
💡 Base: π × 12 = π. Curved side: π × 1 × 3 = 3π. Add them: π + 3π = 4π. Use π ≈ 3.14: 4 × 3.14 = 12.56. The answer is 12.56 square centimeters.
💡 How to solve: Surface Area of Cones
A cone is a circle base plus a curved side. Base: π × r². Curved side: π × r × l, where l is the slant height (along the side, not straight up). SA = πr(r + l). Radius 3, slant height 5: 3.14 × 3 × 8 = 75.36 square units, or 24π. If only the height h is given, find l first: l² = r² + h².
Try a similar one
A cone has a radius of 1 in and a slant height of 3 in. Find its surface area in square inches. Use π ≈ 3.14.
✓ You've got it! Press Next to keep going. Not yet — the answer is . Read the steps above once more.
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Surface Area of Cones — Easy Worksheet 1
Use π ≈ 3.14 unless the problem says "in terms of π". l is the slant height.