Geometry

Area of Circle

Why the area of a circle is πr²

  • Primary school
  • about 3 min
  • 6 of 9 in the family
Not started
r12 sectors→≈ πr (9.42)≈ r (3)A ≈ πr · r = πr²more sectors → closer to a perfect rectangle

Values

A=πr2=π⋅32≈28.274A = \pi r^2 = \pi \cdot 3^2 \approx 28.274

Cut circle into sectors and arrange them in a zigzag. The result approximates a rectangle: width ≈ πr, height ≈ r → area = πr².