Look at the circle in the figure:
The radius is equal to 7.
What is the area of the circle?
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Look at the circle in the figure:
The radius is equal to 7.
What is the area of the circle?
Remember that the formula for the area of a circle is
πR²
We replace the data we know:
π7²
π49
49π
A circle has a circumference of 31.41.
What is its radius?
Area measures two-dimensional space, so we need to multiply length × width. For a circle, we use because it's like fitting r × r squares inside the circle, adjusted by π.
Area is the space inside (π r²), while circumference is the distance around the edge (2π r). Area uses r², circumference uses r.
Usually no! Leaving your answer as 49π is exact and preferred in most math problems. Only calculate the decimal if specifically asked.
Practice your perfect squares! 7 × 7 = 49 is a key multiplication fact. You can also think: 7² = (5+2)² but direct memorization is faster.
Same formula! If r = 3.5, then area = π × (3.5)² = π × 12.25 = square units.
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