7th Grade Math Worksheets PDF | Printable Worksheets - Free Printable

To find the area of a circle, we use the formula:

> Area = π × r²

Where:
- r is the radius (the distance from the center to the edge)
- π (pi) is approximately 3.1416 — we’ll use 3.14 for simplicity unless told otherwise
- r² means “radius multiplied by itself”

Let’s go step by step for each problem.

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Problem 2: Radius = 12 cm

Step 1: Write the formula
→ Area = π × r²

Step 2: Plug in the radius
→ Area = π × 12²

Step 3: Calculate 12²
→ 12 × 12 = 144

Step 4: Multiply by π (use 3.14)
→ 3.14 × 144 = ?

Let’s compute:
3 × 144 = 432
0.14 × 144 = 20.16
Total = 432 + 20.16 = 452.16

✔ So, Area = 452.2 cm² (rounded to one decimal place, like the example)

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Problem 3: Radius = 8 cm

Step 1: Formula → Area = π × r²
Step 2: Plug in → Area = π × 8²
Step 3: 8² = 64
Step 4: 3.14 × 64 = ?

Compute:
3 × 64 = 192
0.14 × 64 = 8.96
Total = 192 + 8.96 = 200.96

✔ Rounded to one decimal: 201.0 cm²

Wait — let’s check with more precise π (3.1416):
3.1416 × 64 = 201.0624 → still rounds to 201.1 cm²? Hmm.

But the example used 7² = 49, then 3.14 × 49 = 153.86 → rounded to 153.9, so they’re using π ≈ 3.14 and rounding to one decimal.

So for consistency:

3.14 × 64 = 200.96 → rounds to 201.0 cm²

Actually, 200.96 rounded to one decimal is 201.0 — yes.

But let me double-check:
In the example: π × 49 = 3.14159... × 49 ≈ 153.938 → rounded to 153.9 — so they’re using actual π value and rounding final answer to one decimal.

So better to use calculator-style precision:

For Problem 2: π × 144 ≈ 3.14159265 × 144 ≈ 452.389 → rounds to 452.4 cm²

Wait — but the example says 153.9 for r=7.

Let’s verify example:
π × 7² = π × 49 ≈ 3.14159265 × 49 = 153.93804 → rounded to 153.9 — correct.

So for Problem 2:
π × 144 = 3.14159265 × 144 = 452.38934 → rounds to 452.4 cm²

Similarly, Problem 3:
π × 64 = 3.14159265 × 64 = 201.06193 → rounds to 201.1 cm²

I think we should follow the example’s method — use π as is, calculate, round to one decimal.

So correcting:

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Problem 2: r = 12 cm

Area = π × 12² = π × 144 ≈ 452.389 → 452.4 cm²

Problem 3: r = 8 cm

Area = π × 8² = π × 64 ≈ 201.062 → 201.1 cm²

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Problem 4: Radius = 10 cm

Area = π × 10² = π × 100 ≈ 314.159 → 314.2 cm²

Problem 5: Radius = 5 cm

Area = π × 5² = π × 25 ≈ 78.5398 → 78.5 cm²

Problem 6: Radius = 4 cm

Area = π × 4² = π × 16 ≈ 50.2655 → 50.3 cm²

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Now, let’s fill in the blanks as shown in the worksheet.

For each, the second line is:
“Area of circle = π x ___” → we put the squared radius here.

Third line: “Area of circle = ___ cm²” → we put the final rounded answer.

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Final Answers:

2)
Area of circle = π x 12²
Area of circle = 452.4 cm²

3)
Area of circle = π x 8²
Area of circle = 201.1 cm²

4)
Area of circle = π x 10²
Area of circle = 314.2 cm²

5)
Area of circle = π x 5²
Area of circle = 78.5 cm²

6)
Area of circle = π x 4²
Area of circle = 50.3 cm²

All calculated using π ≈ 3.14159265 and rounded to one decimal place, matching the example.

Final Answer:
2) 452.4 cm²
3) 201.1 cm²
4) 314.2 cm²
5) 78.5 cm²
6) 50.3 cm²