Area of the circle?

A normal-level "Area" problem.π is simply "how many radius-squares fit in a circle". That is why we multiply by 3.14.

Givenπ = 3.14

Hints

1. A circle's area is "radius × radius × π". The point is that it uses the radius, not the diameter.
2. First "radius × radius": 5 × 5 = 25. That is the area of a square whose side is the radius.
3. The circle is 3.14 times that square. 25 × 3.14 is the answer.

Answer 78.5cm²

More "Area" problems

• Area of the inner triangle?
• Area of triangle DOA?
• Area of quadrilateral ABCD?
• Area of the overlap?
• Total area of the two crescents?
• Area swept by the square?

Browse by idea

• Circles and sectors — multiply by π once, at the very end
• Back to why the formula works

Area Problems (43)　Standard Problems (42)

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